Я надела резиновые сапоги, потому что на улице мокро.

Because the verb is in the past tense feminine singular.

Russian past tense agrees with the subject in gender and number:

• надел = he put on
• надела = she put on
• надело = it put on (rare in this kind of sentence)
• надели = they put on

So Я надела tells us the speaker is female. A male speaker would say Я надел.

Yes, Russian often does drop subject pronouns when the meaning is clear.

So both are possible:

• Я надела резиновые сапоги...
• Надела резиновые сапоги...

Including Я can make the sentence feel a bit more explicit or contrastive, but it is not always necessary. In beginner sentences, Я is often kept because it makes the structure clearer.

Not exactly.

• надела = put on (the action of putting the boots on)
• носила = wore / was wearing (having them on, or wearing them over time)

So this sentence focuses on the moment of dressing:
I put on rubber boots, because it was wet outside.

If you wanted to talk about the state of wearing them, you would use a different verb.

This is a very common question.

• надеть means to put on an item of clothing
• одеть means to dress someone

So:

• надеть сапоги = to put on boots
• одеть ребёнка = to dress a child

A useful memory trick is:

• надеть что? = put on what? → clothes, shoes, hat, etc.
• одеть кого? = dress whom? → a person

In your sentence, надела резиновые сапоги is correct because the speaker put on boots.

It is in the accusative case, because it is the direct object of надела.

The speaker put on what?
резиновые сапоги

For inanimate plural nouns, the accusative form is usually the same as the nominative:

• nominative: резиновые сапоги
• accusative: резиновые сапоги

So even though the case is accusative, the form looks unchanged here.

Russian normally uses the plural for things like shoes, boots, gloves, and socks when talking about the pair as a whole.

So:

• сапоги = boots
• ботинки = shoes
• перчатки = gloves

Using singular would usually mean just one boot:

• сапог = one boot

So надела сапоги means put on (her) boots, meaning the pair.

Because the adjective must agree with the noun it describes.

Here, сапоги is:

• plural
• accusative
• inanimate

So the adjective takes the matching plural form:

• резиновый сапог = one rubber boot
• резиновые сапоги = rubber boots

Russian adjectives change depending on gender, number, and case, so the ending changes to match the noun.

Потому что means because.

• потому что introduces a reason clause
• потому by itself usually means that’s why / for that reason, not because

So in your sentence:

• Я надела резиновые сапоги, потому что на улице мокро. = I put on rubber boots because it’s wet outside.

Compare:

• На улице мокро, потому я надела резиновые сапоги. = It’s wet outside, so/that’s why I put on rubber boots.

Both are possible, but they are structured differently.

Because потому что introduces a subordinate clause.

Russian normally uses a comma before conjunctions like потому что when one clause explains the reason for another:

• Я надела резиновые сапоги, потому что на улице мокро.

The comma separates:

1. the main clause: Я надела резиновые сапоги
2. the reason clause: потому что на улице мокро

This is very standard Russian punctuation.

Literally, yes, на улице is on the street. But very often it means outside / outdoors.

So in everyday Russian:

• на улице холодно = it’s cold outside
• на улице темно = it’s dark outside
• на улице мокро = it’s wet outside

It does not necessarily mean the speaker is specifically talking about the road itself. It is a very common idiomatic way to say what the weather or outdoor conditions are like.

Because мокро here is not describing a specific noun. It is used in an impersonal way to describe the general condition outside.

Russian often uses neuter adverb-like or predicative forms for weather and environment:

• холодно = cold
• тепло = warm
• темно = dark
• мокро = wet

So на улице мокро means it is wet outside.

If you were describing a specific noun, you would use an adjective:

• улица мокрая = the street is wet
• плащ мокрый = the raincoat is wet

But here the idea is broader: the outdoor conditions are wet.

Yes, it corresponds to the English is wet, but Russian often omits the verb to be in the present tense.

So:

• на улице мокро literally looks like outside wet
• natural English: it is wet outside

This is normal in Russian:

• Он дома = He is at home
• Я занят = I am busy
• Сегодня холодно = It is cold today

So there is no missing word from the Russian point of view.

Yes, Russian word order is fairly flexible, though some versions sound more natural than others depending on emphasis.

For example:

• Я надела резиновые сапоги, потому что на улице мокро.
  Neutral and natural.

You could also say:

• Потому что на улице мокро, я надела резиновые сапоги.
  This puts more focus on the reason first.

Russian word order often changes for emphasis, rhythm, or context, but not every order sounds equally natural in every situation. The original sentence is a very standard, neutral version.