The video above contains a 10-minute long explanation from Khan academy covering the basics of angles: how they're formed, types of angles, some vocabulary about angles and a little information about degrees. You only need to watch the first six minutes of this video.
The above video shows you how to use a protractor to measure angles.
The number of degrees in an angle is unrelated to the length of its lines.
An angle's measure has nothing to do with the direction the angle is facing.
Study and practice
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what is an angle
types of angles