Its the metadata of objects like views, triggers, procedures.

You can query it, using a open ended like clause on the definition column for the table name in question

SELECT * FROM sys.sql_modules WHERE definition LIKE '%tablename%'

If it brings anything back you know you need to change them objects.

Its not a 100% complete list as you may have processes on other servers, systems, apps which reference the table, so you would need to do a complete invesitgation as to what connects to the DB, and loop through source code or jobs etc to find out what else will break.

Or you could just go gung-ho and change the table and wait to see what breaks.