Use this tag for questions related to symbolicating a crash report/log. Symbolication replaces memory addresses with human-readable function names and line numbers.
Quoting the Developer.Apple page:
Symbolication - resolving backtrace addresses to source code methods and lines.
Usually, symbolicatecrash is found in questions that are tagged with ios, iphone and/or xcode, so if you are using this tag, please think about whether you need these tags too.