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)