One way to describe woodworking is the creation of a repeatable pattern of angles in wood. A basic table is a flat surface with 4 legs protruding at a 90° angle. A box is similar, just with solid sides.
To be successful at woodworking you will need the tools to create accurate angles. They will be drawn on, cut, clamped, and glued.
Enter the square. A good carpentry square, T-Square or L-Square square will allow you to draw straight lines, measure lengths, and correctly create 45 and 90-degree angles. Using a sliding t-bevel square will open that up to just about any angle. Heck, it even gets fancier. Below I include a digital version that will give you a readout of the angle you are creating.
Ultimately the main three squares that I have used extensively are the carpenter Square, the T square, and the L Square. If you are doing a lot of complex angles then you should consider adding the T bevel sliding Square as well.

Carpentry Square

Carpentry squares(aka Speed Squares) are neat little tools. It gives you straight edges and marks for different angles. you pivot the tool around one of the labeled points. This allows you to draw in any angle on your work. As these are usually on the smaller side you will also likely need one of the longer straight edges to extend lines on larger projects.

Honestly, these are all very similar. You should be able to find them at just about any hardware store. Here is a link to one if you’d rather do it that way.

L-Square

L squares our little more versatile and marking angles. They do not have the benefit of a head which secures them and predetermines the angle to mark. When you lysing this tool you will likely need to measure out and points to get you your angles.

As with all squares you are just looking for something approximately the right size. Here is a link.

T-Square

T-squares are great for t squares are great for right angles. They have a head which slides down over one edge of your work surface. The long tail allows you to quickly draw in long straight lines at 90° to you’re Edge. These also work as a general straight edge.

These should even be able to find at most box and craft stores. Here’s an affilate link.

T Bevel Sliding Square

By I, Just plain Bill, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=2486051

The final Square I’ve seen use the lot is the T bevel sliding Square. She’s not one that I have used much in my woodworking career but I have seen them in many shops. Including my grandfather’s. The idea is to create a t square that is an any angle. It has a ‘head’ which slips over one edge of the work and a straight edge to mark the angle. This is a neat version which gives you a digital readout of the angle you will create.