When available this allows you to select the font you wish to view the emulation in.
Note that only "mono spaced" fonts (non-proportional) may be used in the terminal emulation environment. In addition, the fonts that may be used must be licensed by your organization by the owner of the font Intellectual property. While many fonts are free, others are licensed base on the usage and size of the organization.
This checkbox toggles whether the terminal emulation text is stretched to fit the current area of your screen containing the web terminal emulator. When checked, text will fill the area; when unchecked, text will maintain a consistent shape, which some users prefer.