'Times' is mostly used only in mathematics. If someone asked you how to calculate the volume of a cube, you could say, You multiply the length times the width times the height (or depth).
However, in normal everyday speech to describe measuring things, we usually just say 'by.' How big is the bedroom? Oh, about 15 feet by 20 feet. That's how we get expressions like 'two-by-four,' which is a common measure of lumber (wood): two inches by four inches (in cross-section). That is, if it's clear that the measurement must be in feet or inches, we usually don't even mention the units.
We also use 'by' when reading the abbreviation 'x,' like on dimensions of something you buy at the store. So for example,
15" l x 10" w x 2 3/4" d
could be spoken as
'fifteen inches long by ten inches wide by two and three-quarters inches deep.' Here 'times' would not be wrong, but it could sound a little out of place. In fact, even in my first math example with the cube, many people would probably just say 'multiply length by width by height.'