There are a few considerations in dating Biblical literature:

Literature considerations: scholars can tell from other ancient resources when similar styles were widespread.

Grammar and language considerations: language and grammar change with time. By comparing to other written resources scholars can figure out when language and grammar reached similar characteristics as a specific Biblical book.

Historical considerations: if an historic event was mentioned in a Biblical book the meaning is that it was written somewhat after that event.

Archeological considerations: Similar texts were excavated and archeologists can figure out by archeological means their date (stratum and carbon 14 testing, etc)