Art is abstract if it has been derived, or abstracted from something real but doesn't bear a close resemblance to what it is supposed to represent, like more traditional art does. Some parts of the art might be recognisable, some exaggerated, some downplayed. Abstract art can be so stylised you can't even recognise what it is, so sometimes when you look at an abstract picture or sculpture you can't tell what it is a picture or sculpture of.
Something is compact if it fits into a small space. The car in the picture is a compact car.
You can compact something when you compress it together so it takes up less space, for example you might compact the ground before you lay pavers on it.
