Bivariate: fancy word for 2 variables. Chances are, you've already worked with bivariate equations in algebra when you have equations like y=2x. X and Y are your 2 variables
Contingency Table: Records the data of 2 or more categorical values. Examples below to make it easier
Relative Frequency: the frequency (how often an outcome occurs) in relation to the total number of outcomes. For example, if you pull 3 red marbles out of a bag of 10 total, then the relative frequency is 3/10
Scatter plot: much like a dot plot, except it's 2-D, so you use the x- and y-axis. Much like plotting a line in algebra, except you don't connect the points and they don't necessarily have to be in a straight line. Oftentimes, they aren't straight. More examples below
Visit this site for more looks at scatter plots: http://www.purplemath.com/modules/scattreg.htm