What do you want to know exactly? How are you working now? A Glyph is any letter, number, symbol what you get in a Font. If you have never used glyphs, than only because you have never written anything, but even asking this question forced you to use glyphs to write words and sentences.
A "character" is an abstract concept to represent the various letters and symbols in a language. A "glyph" is the graphical representation of a character, so the Character "A" will be represented by slightly different glyphs depending on the typeface style.
The Glyphs panel is used to identify the mapping of glyphs to their characters, and to find and insert glyphs that cannot be easily entered from the keyboard.
Can we change the character mapping ?
if so how ?
I am having a problem in indesign, that the line is breaking at a character 005F, so i am trying to look how can we change the mapping ?
How to solve this issue?
The only way to change the mapping is to edit the font.
What part of the answers you've already been given for how to prevent the break at that character are you not understanding?
I think you should buy a license of a new appropriate OTF Font. I doubt that your license of your font would allow editing and I think it would require some higher knowlegde, without that it could cause more costs and damage when you later bring the final PDF to your printer.