Before doing any data analysis, consider what type of data you have. Data fall into two broad categories: continuous and discrete.

Continuous data are usually measurements or observations, (e.g. weight, height) which can take any value in some number range and will have associated units (m, kg, etc).
Discrete data can only take integer (whole number) values. For example, the number of animals in an experiment is discrete. A subset of discrete data is categorical data, where the numbers denote a category, rather than a numerical value, e.g. 1=male, 2=female.