You'll see and draw many two dimensional (2D) structures and reactions. With 2D structures we can only interact with them in 2 dimensions (e.g. you can't rotate the structure out of the plane of the paper or computer screen). We can still show or represent the 3 dimensional (3D) nature of molecules and reactions in 2D. Its very important you learn to draw 3D representations in 2D. Its like perspective drawings you may have encountered in drafting or art class.
For example the structure of L-alanine below. It's OK if you don't know what alanine is yet. The dark wedge to the H atom indicates its pointing toward you, while the dashed wedge to the NH2 group indicates its projecting back away from you.