Tiresias is warning Odysseus not to "raid the beeves" (meaning steal the cows) from the Land of Helios (the sun god). He makes it clear that Helios is able to see, hear, and know everything so if Odysseus and his crew take the cows, Helios will know about it. This, Tiresias warns, will lead to the destruction of the ship and crew. We can assume this will be because Helios will fight or send fighters to Odysseus' ship, so there will be character on character conflict.