Утром я беру зубную щётку и кладу на неё пасту.

Russian very often uses the instrumental case (утром) to say “in/at (a time of day)” in a general, habitual sense.

• утро – nominative, “morning” (as a thing):
  
  • Утро холодное. – The morning is cold.
• утром – instrumental, “in the morning”:
  
  • Утром я беру зубную щётку… – In the morning I take a toothbrush…

You don’t normally say в утро in this sense. For general daily routines, use:

• утром – in the morning
• днём – in/at the daytime
• вечером – in the evening
• ночью – at night

So Утром я беру… literally is “(By) morning-time I take…”, which corresponds to English “In the morning I take…”.

These are aspect pairs:

• брать (беру) – imperfective “to take (regularly / in progress)”

• взять (возьму) – perfective “to take (once, completed)”

• класть (кладу) – imperfective “to put/lay (regularly / in progress)”
• положить (положу) – perfective “to put/lay (once, completed)”

In this sentence we describe a routine/habit (“In the morning I (always) do this”), so Russian needs the imperfective:

• Утром я беру… и кладу… – In the mornings I (normally) take… and put…

If you used perfective:

• Утром я возьму зубную щётку и положу на неё пасту.

…this would usually sound like a one-time future plan:
Tomorrow morning / on that morning I will take the toothbrush and (then) put toothpaste on it.

Because зубная щётка is the subject form (nominative), and in this sentence toothbrush is a direct object of the verb беру.

• Nominative (dictionary form): зубная щётка – a toothbrush
• Accusative feminine singular: зубную щётку

Pattern:

• я беру что? – I take what? → зубную щётку (accusative)
• я вижу что? – I see what? → зубную щётку
• я покупаю что? – I buy what? → зубную щётку

So the adjective зубная → зубную, and the noun щётка → щётку to show they are objects, not subjects.

Same reason as with зубную щётку: паста is the nominative (subject) form, and here it’s a direct object.

• Nominative: паста – paste / toothpaste (as the subject)
• Accusative: пасту – paste / toothpaste (as the object)

Verb: кладу (что?) – “I put (what?)” → пасту.

So:

• Паста закончилась. – The toothpaste is finished. (subject)
• Я кладу пасту на щётку. – I put toothpaste on the brush. (object)

1. она is the nominative form – used only for subjects:

   • Она лежит в ванной. – It (the brush) lies in the bathroom.

2. With a preposition (like на, в, к, с etc.), Russian uses special forms of the pronoun:

   • она → неё (after most prepositions)
   • он → него
   • они → них

So:

• на + она → на неё (onto/on her/it)

We need на неё, because the structure is:

• класть (что?) на (кого? что?)
  
  • кладу пасту на неё – I put paste on it.

You can’t say на она; that’s ungrammatical.
Bare её (without на) would mean “her / it” as a direct object: I see her/it = я вижу её, not “on her/it”.

Russian adds н- to the 3rd person pronouns after most prepositions, to avoid awkward sound sequences.

Base forms:

• его, её, их

After prepositions (к, у, в, на, с, от, для, про, без, из, о, по, под, над, перед, при, между, etc.) they usually become:

• к нему, у неё, на него, для них, etc.

So:

• на + её → на неё, written with н, pronounced [na niˈjo].

This is a spelling and pronunciation rule, not a change of meaning.

The preposition на can mean both “onto” (movement) and “on” (location). The verb tells you which one.

• With verbs of putting / movement (класть, положить, ставить, ложиться, идти, садиться…), на + accusative = onto, to (a surface):

  • кладу пасту на щётку – I put paste onto the brush.
  • сажусь на стул – I sit down on(to) the chair.

• With verbs of being / location (лежать, стоять, сидеть, быть…), на + prepositional = on:

  • паста на щётке – The paste is on the brush.

So here, with кладу, на неё is best understood as “onto it”, though English just says on it.

Yes, both are grammatically correct:

• кладу на неё пасту
• кладу пасту на неё

Russian word order is flexible and often used for emphasis:

1. кладу на неё пасту
   Slight focus on “onto it” (the brush): I put (onto it) paste.

2. кладу пасту на неё
   Slight focus on “paste”: I put the paste (onto it).

In neutral everyday speech, both will sound natural. The original order just slightly highlights the destination first (на неё), then what goes there (пасту).

Russian often omits possessive pronouns (мой, твой, наш, ваш) when ownership is obvious from context, especially with:

• parts of the body,
• clothes being worn,
• personal items commonly associated with one person (like a toothbrush in your bathroom).

So:

• Я чищу зубы. – literally “I brush teeth,” but obviously my teeth.
• Я надеваю куртку. – “I put on (my) jacket.”
• Я беру зубную щётку. – normally understood as “my toothbrush”.

You can say:

• Утром я беру свою зубную щётку…

This is correct and means “my own toothbrush”, a bit more explicit, sometimes a bit more emphatic or contrastive (“not someone else’s”).

Yes:

• зубная паста = toothpaste
• Accusative: зубную пасту

In everyday speech, when it’s clear what paste is meant (in the bathroom, next to the toothbrush), Russians often drop the adjective:

• Передай, пожалуйста, пасту. – Pass me the toothpaste, please.
• Кладу на неё пасту. – I put toothpaste on it.

If you want to be explicit or you’re contrasting types of paste (toothpaste vs some other paste), you’d say:

• …кладу на неё зубную пасту.

Yes, that’s a very common sentence:

• Утром я беру зубную щётку и чищу зубы.
  In the morning I take a toothbrush and brush my teeth.

Difference:

• кладу на неё пасту describes a step of the process: putting toothpaste on the brush.
• чищу зубы describes the main action: actually brushing the teeth.

You can combine them:

• Утром я беру зубную щётку, кладу на неё пасту и чищу зубы.
  In the morning I take a toothbrush, put toothpaste on it, and brush my teeth.

Stresses:

• у́тром – Ú-trom (stress on у)
• беру́ – be-RÚ
• зубну́ю щётку – zoob-NÚ-yu SHCHOT-ku
  
  • зубну́ю – stress on у
  • щё́тку – stress on ё (always stressed)
• кладу́ – kla-DÚ
• на неё́ па́сту – na ni-YÓ PÁS-too
  
  • неё́ – stress on ё
  • па́сту – stress on а

Pronunciation tips:

• щ is a soft long sound like “sh” but softer and longer: approximately [ɕː].
• ё is always pronounced yo and always stressed: щё́тку [ˈɕːɵtkʊ], неё́ [nʲɪˈjo].
• ю after a consonant (зубну́ю) sounds like

ложить (and ложу) is non-standard/incorrect in modern standard Russian. It’s common in colloquial / dialect speech but is considered a mistake in formal language.

The correct verb pair is:

• класть (кладу, кладёшь…) – imperfective
• положить (положу, положишь…) – perfective

So:

• Я кладу пасту на щётку. – correct (habit / process)
• Я положу пасту на щётку. – correct (one-time future)

Avoid я ложу пасту in standard written or careful spoken Russian.