here's your triangle.
A
x
x x
x x
x x
x x
x x
x x
x x
x x
x x
B xxxxxxxxxxxxxxxxxxxxxx C
it is labeled triangle ABC.
There is an angle at point A, point B, point C.
There are labeled angle A, angle B, angle C
They are also labeled angle BAC, angle ABC, angle BCA
The vertex of the angle is the point where the two sides of the angle meet.
These would be the sides that include the angle.
There are 3 sides to the triangle. They are sides AB, BC, and AC. The sides are labeled by their endpoints. The sides are also called line segments.
Two of the sides of this triangle are AB and BC.
The included angle between these sides would be at the intersection of the 2 sides which would be at the common point of the two sides which would be at point B. Angle B, otherwise labeled as ABC or CBA, is included between the sides of AB and BC.