Evolutionary things have to do with how animals (or other things) change over time — this process of change is called evolution.
Scientists that study living things are interested in evolutionary changes in form or behavior. It's not always easy to put the evolutionary pieces together, and scientists often have to rely on fossils to tell the whole story of evolution. Usually, evolutionary changes happen because they help the organism survive and reproduce. Many evolutionary questions are non-physical: How did the domestication of dogs change the behavior of canines from an evolutionary standpoint? When you see the word evolutionary, think "change."