Android keyboard has many features in it. Like, word suggestions, use space-bar to navigate to words in left or right, clipboard to paste frequently used words/phrases etc.
Let's go one by one.
1. Word suggestion feature:
Go to settings>Text correction>Check all the options.
2. Delete one word:
Select, hold the back/delete button and swipe to the left and see the magic. It deletes one or multiple selected words.