What do I do when This error shows up ?

Youd want to update your code to the following:

 if (colInfo.tag == ("Player")){
 var destructible = colInfo.GetComponent ("Destructible") as Destructible;
     destructible.destruct();
     }

Your main issue is, after ("Player"), you dont have a closing brace ) for your if-statement - as well I noticed you also dont have a starting curly brace { for your if-statement either. Now taking a second look, you also technically dont have an ending curly brace } for that if-statement either, so your code will run and the error will go away once you add that closing brace ) - but you probably wont get the results you expected - when you dont specify curly braces with if-statements, it will only read the following line under it, as the "if statement", so only line 8 is considered a part of the if-statement to line 7, and like 9 is considered part of line 6's if-statement.