This is a concept from the study of chemistry. Atoms can be bonded (meaning stuck together) to each other in two different ways:

• A covalent bond happens when atoms share electrons between them.
• An ionic bond happens when one atom removes electrons from another atom, and they are attracted to each other as a result.

If you'd like to understand ionic and covalent bonds better, you can watch this video lesson:

https://www.khanacademy.org/science/chemistry/periodic-table-trends-bonding/v/ionic--covalent--and-metallic-bonds

This topic doesn't come up in conversation much outside of science classes.