TechFlex is a brand name for braided cable sleeve. Usually people use techflex or a similar product to group multiple cables together. For example if you are making a 6 channel audio cable or component video cable and want to keep those wires bundled together you can put them into techflex and you end up with a neat bundle. It is also used to make some of the more "usightly" cables look prettier.
In industry (factories, aircraft, studios) the product serves the purpose of abrasion resistance, strain relief and some other stuff that mose home users aren't particularly concerned about.