If there is something in the lease that you do not understand or agree with, do not sign it. Talk it over with the other person. Do not sign the lease until both of you understand it and can comply with everything in it. Once you sign the lease, you are bound to it, and a court will probably enforce it. If any part of the written agreement is changed by crossing out or writing in the change, both of you should initial the change. Be sure that all blanks on a pre-printed lease form are filled in or marked through before you sign.
A landlord has no legal obligation to give tenants a copy of the lease. A tenant should insist on signing two copies of the lease so that each party can have a fully executed document. Each of you should keep a signed copy of the lease, at least until the tenant has moved out and a mutual agreement has been reached about the return of the security deposit.