The Text Block means adding the content body and then edit the way the users want with the given features. Even this section states three parts namely the General, the Style and the Custom CSS.  Now, the General section can be best understood with the picture below:

Themelines Page Builder Text Block

Themelines Page Builder Text Block

The user can also add HTML code as well as shortcodes in text block section.

Again, the Style section lists the following features:

Themelines Page Builder Text Block

Themelines Page Builder Text Block

Themelines Page Builder Text Block

Themelines Page Builder Text Block

Themelines Page Builder Text Block

Finally, the Custom CSS section is portrayed in this way,

Themelines Page Builder Text Block