How do I remove these gaps in this paragraph?

1. Choose the correct language in your paragraph style. (Don't use a character style here)
2. Select in the program settings the correct dictionary for the same language.
3. Allow hyphenation in your Paragraph Settings.
4. Work in the Paragraph Style on the finetuning in the justification section.

Dealing with what are called "rivers" in justified text can be dealt with either manually by tracking out the text to fill in the spaces or in more automated ways such as can be seen in the video found here: https://www.youtube.com/watch?v=40nhT0O48uI.