'Take over' is a phrasal verb which means to begin to do something that someone else was doing, or to take control of something. You could 'take over' a task from someone else or 'take over' a company for example. This is a common phrasal verb used in both social and professional contexts.

1. I've been driving for hours now. Do you mind taking over for a while?
2. Excitement about the event has been taking over the country. Everyone seems to be talking about it!

1. I took over from the new employee at the cash register because she was struggling to deal with the long line of customers.
2. That company are buying up all their competitors. They seem to want to take over the entire industry.