It is not really necessary to have "this" in the title line; the line translates basically to "My mother told me", þat is just a common formality of Norse and the Norse languages that isn’t needed in English.
> fagrar árar
This is plural.
> stýra dýrum knerri
I would translate "dýrum" to something like noble, or valuable.
> Þél höggr stórt fyr stáli, stafnkvígs á veg jafnan
This is saying that a file -- I assume this is a metaphor for the choppy waves of a storm -- strikes in front of the steel of the prow, "on its smooth path". Stafnkvígr is a ship, a kenning of stafn+kvígr ("prow-bull").
> andærr jötunn vandar
This is another kenning, meaning storm. "Enemy of the post/tree", basically, as wind strikes down trees or tall structures. Skaldic poetry is big on metaphors. Andærr means adverse.
> en svalbúinn selju
The cold-clad enemy of the willow (selja is in the genitive case here referring to the various euphemisms for enemy, I'm honestly not sure which).
The last two lines are rather difficult to write poetically in English, but the gist of it is that the wind and storm is beating against the gilded front of the ship.
this song appeard in the 4th season of the tv production 'vikings' that centers around the life of ragnar lodbrok and his settlement in kattegat. It is sung by Harald Fairhair, who is known in the series as Harald Finehair, the future king of all norway and his good friend Halfdan the Black.
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https://www.youtube.com/watch?v=-SUpsLxUrKQ
The lyrics here consist of 2 poems of Egils Saga, found there in chapter 40 and 57.