plural of 'rub': instances of rubbing; (figuratively) difficulties, snags, or obstacles in a plan or situation.

こする行為の複数形；（比喩で）障害、問題点

third-person singular present of 'rub': to move something back and forth over a surface with pressure, typically to clean, warm, soothe, or create friction.

（力を加えて）往復してこする（こすって汚れを落とす・温める・なでるなど）

to cause someone to feel annoyed, offended, or uncomfortable (often used in the phrase 'rub(s) someone the wrong way').

（人の）気に障る、（人を）不快にさせる（比喩的）