What should I know about an 18 months contract for an entry level position?

Graduated in June, working a minimum wage job at a friend's clothing/print store and would like to do something in biology, my field.

A recruiter (or maybe an external agency?) for a pharmaceutical company originally asked for a 6 months position and later followed up if I was interested also in a 18 months position.

I understand that an entry level biology job isn't going to be pretty, a lot of repetitive work. 6 months to a year is fine. But I don't know about a year and a half.

Am I forbidden to leave during that 18 months?

EDIT: Is it rude to ask the recruiter (e-mail/LinkedIn) what the company is?

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