The sketch shows a fatty acid. Almost all have an even number of carbon atoms. The one shown is much less common than those that have 16 or 18 carbon atoms. Note the long chain of non-polar organic groups terminated by a carboxyl group shown in red. Click if you don't know the notation for carboxyl groups. This carboxyl group can ionize weakly. At neutral pH in water, it is highly ionized. With much of the molecule non-polar and its end charged and highly polar, it prefers to orient at the interface between polar and non-polar materials. This confers detergent properties. The salts of fatty acids are soaps.
This molecule is glycerol. Its common name is glycerine. Its alcoholic OH groups form esters with fatty acids as shown in the next figure:
A fat is the triester of fatty acids with glycerol. The fatty acids may be the same or different. Note that fats have an abundance of H atoms and few O atoms. They are slightly oxidized but much less so than sugars. They are very high energy foods because so much more oxidation is possible. Metabolism of fats .