I get on very well with my sister. = have a very good relationship with my sister
How are you getting on? = What progress are you making? e.g. with an exercise or in general
Is it difficult to get to know people? = meet people and make friends
We should get rid of these books = sell them/throw them away; remove them
My alarm wakes me up at 7, but I don't usually get up = get out of bed until 7.15
Those boys get on my nerves = annoy me and make me angry. They don't do any work.