Lift acts perpendicular to the wing and drag acts along it, and the ratio between them is the glide ratio — how far you go for every metre you fall. The wing's job is to make the air turn downwards, and the whole of the design is in the shape of the curve it makes the air follow.
A wing makes the air turn. Turning the air downwards means pushing it down, and by the third law the air pushes back — upwards. That is lift, and the amount of it depends on how much air is turned and how fast.
But turning the air also costs you: the wing has skin friction against the air, and the tilted wake leaves a little energy in turbulence behind it. That second cost is induced drag, and it goes as the square of the lift, which is why a glider flies fast and flat or slow and steeply, and why the best glide is at some particular speed rather than at any speed.
Lift is linear in the angle of attack only while the flow stays attached. Past about fifteen degrees the boundary layer on the upper surface separates, the wing stops turning the air cleanly, and the lift collapses — while the drag rises steeply. That is a stall, and the airfoil drawn here is a NACA 2412, a conventional shape that stalls at about sixteen degrees.
Watch the lift curve as you sweep the angle past the stall: the trace turns over, the drag goes up like a wall, and the glider on the right stops flying and starts falling.