Read the following quick sheet: Linear Algebra Explained in 4 Pages
You should be familiar with the following concepts:
- adding vectors
- matrix multiplication
- matrix inverse
- how to visualize lines and planes and hyperplanes; dot product
- systems of linear equations
- eigenvalues
An excellent visual introduction to Linear Algebra can be found here.
It is highly recommended that you watch the above video series.
For those looking for a more in-depth treatment of linear algebra, you should check out MIT's 18.06 Linear Algebra Course