ما معنى Cache line, set-associative cache؟

Memory moves between the levels of the hierarchy in fixed blocks called cache lines, 64 bytes on current x86 processors. In a set-associative cache with $S$ sets of $W$ ways, a line can be stored only in the set given by bits of its address, in any of that set’s $W$ slots; the cache holds $S \cdot W$ lines.