Unless you misbehave, a landlord may not kick you out in the middle of a lease.
A lease for a fixed length of time (a year, or 6 months, for example) is binding on both parties. You promise to pay the rent for that period, and he promises to let you stay for that period. He cannot arbitrarily end the lease before the period expires (unless the lease so provides, which is rare).
But if you fail to pay the rent, start wrecking the place, or breach a provision of the lease in some significant way, the landlord may give you a notice telling you to cut it out or get out. And if you fail to do either within the time specified in the notice (usually about 3 days), he may bring a lawsuit to evict you.