It literally means "to write", but it's commonly used to refer to urination, especially in a formal context.
Here are some other ways to say "pee" in Russian, depending on the situation:
* "Мочи́ться" (mochítsya) - This is a more formal and medical term.
* "Сходить в туалет" (shodít' v tualet) - This means "to go to the toilet" and is a common way to refer to urinating.
* "Пописать" (popísat') - This is a more informal and casual way to say "pee".
It's best to use "писа́ть" in most situations, unless you're in a very informal setting.