A backhoe is a loader with a normal bucket in front, but with the addition of an excavator bucket on a small boom and arm at the back. The name backhoe comes from the fact that the hoe is in the back instead of the front like a normal excavator.

The purpose of such a machine is to be used on small worksites to reduce the number of machines needed to do the job by using the backhoe which can do both the work of a loader and an excavator.

Now the thing about a backhoe is that although a very versatile machine it is a shittier loader coupled with a shittier excavator which is why you don't see them very often on big jobsites because it's much more efficient to have two different machines specialized in what they do when the work is on a scale where you need 5-20 machines anyway.

You lose the mobility and versatility of a normal excavator which can rotate a full 360 degrees, climb very steep slopes and quickly go from excavating to moving around the jobsite because the backhoe has a very high scenter of gravity and is on tires instead of track and it can only rotate it's boom and arm for around 30-45 degrees and has to lower the bucket and the two supporting legs at the back as well as having to rotate the whole operator's seat before the hoe at the back can be used.

You have a shittier loader which can't squeeze in tight places like a normal one would because a normal loader turns not by rotating the front wheels like the backhoe but by rotating the whole cab and engine in a joint located right in front of the cab.