Explanation
To make an axis bold, simply right click it, select format, and then click on Font to choose Bold:

None of the other options are valid ways to make the axis bold.

Read more about editing axis: https://help.tableau.com/current/pro/desktop/en-us/formatting_editaxes.htm

Explanation
You can create aliases (alternate names) for members in a dimension so that their labels appear differently in the view.
Aliases can be created for the members of discrete dimensions only. They cannot be created for continuous dimensions, dates, or measures.
To create an alias:

1) In the Data pane, right-click a dimension and select Aliases.
2) In the Edit Aliases dialog box, under Value (Alias), select a member and enter a new name.

* To submit your changes: In Tableau Desktop, click OK.
On Tableau Server or Tableau Online, click the X icon in the top-right corner of the dialog box.
When you add the field to the view, the alias names appear as labels in the view. For example:

Explanation
When you track data in Excel spreadsheets, you create them with the human interface in mind. To make your spreadsheets easy to read, you might include things like titles, stacked headers, notes, maybe empty rows and columns to add white space, and you probably have multiple tabs of data too.
When you want to analyze this data in Tableau, these aesthetically pleasing attributes make it very difficult for Tableau to interpret your data. That's where Data Interpreter can help.

Explanation
From the data pane, simply right click on the dimension, choose geographic role, and then select the appropriate role as follows:

Explanation
From the official Tableau website: