The verb get has various definitions and uses. Here are the most frequent ones:
1) to receive: get a present
2) to acquire as a result of effort, earn: get a graduate degree; get a high mark in an exam.
3) to take, go after, bring: Get me a glass of water, please.
4) to buy: get some meat at the butcher´s; get a new car.
5) to arrive at, reach: get home; get to the top of the mountain
6) to understand: get what somebody means; get an idea
7) to become: get irritated/sad/happy
(Source: American Heritage Dictionary of the English Language)