Learn Hardcore Hindi: टूथब्रश और टूथपेस्ट दाँतों के लिए हैं। - The toothbrush and toothpaste are for the teeth.

Because they are common English loanwords in Hindi. Hindi often uses borrowed words for modern everyday objects, especially products and technology, and writes them in Devanagari.

So:

टूथब्रश = toothbrush
टूथपेस्ट = toothpaste

This is very normal in modern Hindi. You may also hear more traditional words in some contexts, but these borrowed forms are widely understood and very common.

What does और mean here?

और means and.

It joins टूथब्रश and टूथपेस्ट into one combined subject:

टूथब्रश और टूथपेस्ट = toothbrush and toothpaste

Because two things are being linked, the whole subject is plural.

Why is दाँतों used instead of दाँत?

Because के लिए requires the noun before it to be in the oblique case.

Here is the pattern:

direct plural: दाँत = teeth
oblique plural: दाँतों

So:

दाँत = teeth
दाँतों के लिए = for teeth

This is a very important Hindi pattern: when a noun is followed by a postposition such as , , , , etc., the noun often changes into its oblique form.