#1 touch on v. refer to or discuss briefly. wn
#2 touch on v. be relevant to; "There were lots of questions referring to her talk"; "My remark pertained to your earlier comments". wn
#3 touch on v. restore by replacing a part or putting together what is torn or broken; "She repaired her TV set"; "Repair my shoes please". wn
#4 touch on v. have an effect upon; "Will the new rules affect me?". wn
vizzz