This is one of the basic crochet stitches that beginner's should learn, a Slip Stitch. Here is a photo tutorial to guide you in your crochet journey.
In an English books, you can read it like this.... sl st.
A slip stitch or sl st is the smallest crochet stitch you can make.
Step 1: Make a foundation chain.
Step 2: Insert the hook under two threads (or yarns) at the top of the required stitch. Catch the threads (or yarn) with the hook.
Step 3: Pull a new loop through the three loops on the hook made.
Step 4: Repeat step 1-3
This is what the slip stitch looks like in right side
This is what the slip stitch looks like in wrong side.