Adipose tissue is probably the easiest thing to identify. The only other things that looks anything like this is the lung, and there are some obvious differences that are pointed out on the lung page.
What you are seeing in this image resembles a sponge, with lots of spaces. What look like hundreds of empty spaces on this image are where fat was stored inside the cells. When the tissue is processed, the fat dissolves in the processing chemicals and leaves the space.
The bar labeled "a" indicates the width of one adipose cell (adipocyte). The light purple dots you see inside the cells are an artifact of process used to make the images, and do not represent real structures. The arrow points to the nucleus of one adipocyte. The nucleus and cytoplasm are pushed to the outside of the cell by the large fat droplet.