What do floats mean?

I’m reading an answer, which says something about "floats" in latex, bold displayed below. What does that mean?

First of all, as you already mentioned clearpagenot only ends the page (or column in two column mode) but additionally it flushes out all floats that have been deferred. On the face of it that might be a good idea but consider the following situation: you have one float waiting which is just 1/3 of the page size. Now with newpage you start a new page and then the float algorithm (see description of this algorithm for details) would kick in and try to place waiting floats onto the next page (and most likely would assign the waiting float to the top area of the next page. In contrast clearpagewould also output this float but on a page of its own.