An ebb(tide) does not wait for a slow man.
Note: The Béarla equivalent for this seahfhocal would be “Time and tide wait for no man”.
Note also: There are two meanings to “trá” in Irish. The more common meaning is “beach” and in that case “trá” is feminine. For the other usage (such as in this seanfhocal) the noun is masculine and means “ebb” (as in tide).
Note also how the negative particle “Ní” causes the verb that follows it to be lenited. (Lenition or “séimhiú” is represented with a dot over the lenited letter in gaelic font and a trailing “h” in roman font.) Look at the other proverbs (Seanfhocail Eile) that begin with “ní.” Some appear to violate this rule. Look closer and you will see that words that are not lenited are not verbs at all, but nouns. In all of those sentences “Ní:” is the entire verb (not just a particle), and it is just the negative form of the copula “Is.” Please don’t be confused by the fact that “Ní” can do double duty.