On tables:
Tables are used for data representation, rather than the (formerly) popular method of using them for page layout. If you have to display a series of numbers/dates/something along those lines in a column & row format, then it's safe to know how to use tables. That's their purpose.
On Frames:
There's very little use in knowing frames, but you might as well know it for the sake of knowledge. There may well come a day that frames are effective and accepted, but until then the only frame related concept you should really know is the iframe tag. Follow w3schools.com's guide to html and you'll get the gist for what you need to know.