A poem about a bad poet(says Catullus) who thinks he is a good poet. When Catullus is critical of you, you had usually better duck, but here he sees a need to make allowances, and recognise that a capacity for self-deception is part of human nature. One likes him all the better for it.
There is all sorts of interesting stuff here about Roman books if that is your interest. The reference at the end to carrying baggage is to one of Aesop’s fables, about a man who has two bags: one at the front, in which he keeps his neighbour’s shortcomings where he can see them, and one kept out of sight on his back, containing his own.
To listen, press play: