"what is a learning management system? " is an example of which sq3r step?

SQ3R is an acronym used to help with understanding what you're reading. Here are the steps in the SQ3R process:

Survey
For this step, skim through the text. Look at any headings, titles, graphs, or illustrations without reading any of the actual words in the body of the writing. This gets you familiar with what they're about to read.

Question
Come up with questions based on the headings you've read. They won't be specific questions. Examples could be: "What is this article about?", "What is this chapter trying to tell me?"

Read (1st R)
Now is the time to read the text you have been given. Use the questions you came up with in the Q step to be active in your reading.

Recite (2nd R)
Try to summarize and think to yourself about what you just read from memory, without looking back at the text. Use your own words instead of copying what you just read. Try to answer questions you came up with from the Q step. 

Review (3rd R)
Using your own words, come up with a sentence that best tells what the purpose of the passage is.

Now that we have the steps in the process, let's take a look at your question. "What is a learning management system?" seems to fit best in the Question step. It's something you would ask yourself about the main purpose of the passage and can be answered during your active reading.