Answer:
The term "pseudo" basically means false. Pseudo-psychology is a strain of pseudoscience, as psychology is a strain of science, so I'll just address pseudoscience in general.
Pseudoscience refers to anything that tries to look really similar to science in order to appear legitimate and trustworthy; it usually borrows key words or jargon that people generally recognize as being scientific terms to try to seem more important. However, pseudoscience isn't true science - it doesn't rely on experiments or objective data.
The pseudoscience people most frequently encounter is what is shown in weight-loss commercials, which just doesn't hold up under scrutiny.