To perform a basic search in Gmail, press / (forward slash) to move to the Search box, type in your keywords and press Enter.
This is a Google search that we are talking about here, which is pretty powerful. But, of course, the more info you put in the better the results.
When you press Enter, the focus moves to the list of email messages that it found, and you can arrow through the Search results to find what you are looking for.
To get back to the Inbox, press G then I (Go to Inbox).
If you get stuck in the Search and you just want to get back to your list of email messages, press Escape.
Note: If you use a screen reader, you may need to switch the “virtual cursor” off so you can use these shortcuts. Press Insert (or Caps Lock) + Z in JAWS or Insert (or Caps Lock) + Space in NVDA and Narrator.
Microsoft Edge and Mozilla Firefox work the same as Google Chrome for Basic Search in Gmail.