Is the word teachers have an a apostrophe?

Depends, if the Word "teachers" is a plural noun, and refers to multiple teachers then use an apostrophe. Example:

The teachers' club handed out free pencils.

If the world "teachers" is singular, and only refers to one teacher, then use an apostrophe like so:

My teacher's dress is very red.

If you are not referring to possession at all, and nobody is owning anything in the sentence, then put no apostrophe