Need some help and advice

My sister in the SF Bay Area CA is buying a home with a pool. She
doesn't have a clue about pools... how to maintain the pool / water
etc.

Some people say buy some tablets, buy an automatic moving cleaner.
Others say get a pool service.
What should she do ? What tablets are these ? Are these tablets
expensive ?
is it easy to do by oneself ?

Would any one with experience, pls shed some light on this.

Thanks
Linda