Kan du lägga lite tandkräm på min tandborste?

Kan du literally means Can you. In Swedish, this is a very common way to make a request, just like in English.

So:

• Kan du lägga ... ? = Can you put ... ?

Even though it looks like a question about ability, it usually functions as a polite request in everyday speech.

A slightly more polite or softer version would be:

• Skulle du kunna lägga ... ? = Could you put ... ?

It is normally polite and completely natural in everyday Swedish. It does not usually sound rude.

Swedish often uses simple structures that may seem more direct to English speakers, but they are perfectly normal. If you want to sound softer or more formal, you could say:

• Kan du lägga lite tandkräm på min tandborste, tack?
• Skulle du kunna lägga lite tandkräm på min tandborste?

Adding tack can also make it sound friendlier.

Lägga is the natural verb here because it means to lay / put / place something down, especially when talking about putting something onto a surface.

In this sentence, the toothpaste is being placed on the toothbrush, so lägga works well.

Some useful comparisons:

• lägga = lay/put something down horizontally or onto something
• ställa = stand/set something upright
• sätta = set/put, often used in other contexts, but less natural here

Because toothpaste is being applied onto the brush, lägga sounds idiomatic.

Lite means a little or some.

In this sentence:

• lite tandkräm = a little toothpaste / some toothpaste

English often uses some in this kind of request, while Swedish commonly uses lite.

It makes the request sound natural, because you normally only want a small amount of toothpaste.

Because tandkräm is being used as an uncountable noun, like toothpaste in English.

So Swedish says:

• lite tandkräm = some toothpaste

not:

• en tandkräm in this context

You would only use en if you were talking about a tube or a type of toothpaste in a different sense, not the substance being put on the brush.

Because the toothpaste goes on the toothbrush, not in it.

So:

• på = on
• i = in

A toothbrush is treated as a surface here, so på is the correct preposition.

Compare:

• på bordet = on the table
• i lådan = in the drawer

In Swedish, when you use a possessive word like min, din, hans, hennes, vår, etc., you normally do not also use the definite ending or a separate definite article.

So you say:

• min tandborste = my toothbrush

not:

• min tandborsten
• den min tandborste

This is different from some other structures in Swedish where double definiteness appears, but with possessives like min, you normally just use the possessive + noun.

Because tandborste is a common gender noun (an en-word) and it is singular.

So the possessive must match that:

• min for singular en-words
• mitt for singular ett-words
• mina for plural nouns

Examples:

• min tandborste = my toothbrush
• mitt äpple = my apple
• mina skor = my shoes

Since en tandborste is singular and an en-word, min is correct.

Because Swedish forms compound nouns by writing them as a single word much more often than English does.

So:

• tand = tooth
• kräm = cream
• tandkräm = toothpaste

and:

• tand = tooth
• borste = brush
• tandborste = toothbrush

This is completely normal in Swedish. English often uses two words or a closed compound depending on the noun, but Swedish strongly prefers one combined word.

Yes. It follows standard Swedish question word order for a yes/no question:

• Kan = verb
• du = subject
• lägga lite tandkräm på min tandborste = rest of the sentence

So the pattern is:

• Verb + subject + infinitive/main content

This is very similar to English:

• Can you put some toothpaste on my toothbrush?

The sentence is completely standard and natural.

A more formal or gentler version could be:

• Skulle du kunna lägga lite tandkräm på min tandborste?
• Kan du lägga lite tandkräm på min tandborste, tack?
• Kan du vara snäll och lägga lite tandkräm på min tandborste?

These all mean roughly the same thing, but the tone changes a little:

• Skulle du kunna ... = more polite / softer
• ..., tack = friendly and polite
• vara snäll och ... = please be kind and ...

This is a very common point of confusion.

• lägga = to lay / put something somewhere
  
  • it usually takes an object
• ligga = to lie / be lying somewhere
  
  • it describes position, not the action of placing

Examples:

• Kan du lägga tandkrämen på bordet? = Can you put the toothpaste on the table?
• Tandkrämen ligger på bordet. = The toothpaste is lying/is on the table.

So in your sentence, lägga is correct because someone is actively placing the toothpaste onto the toothbrush.