The Rig Veda VIII.63 is dedicated to Indra, except the last 12th Mantra.
The translation given by Stephanie W. Jamison and Joel P. Brereton is as follows;
For us are the Rudras [=Maruts] in their profusion and the mountains
of one accord at the Vr̥tra-smashing, where the call is “Carry (the
day)!”
The steadfast one who has been established for the praiser and
presser—with him, Indra, as their chief let the gods help us.
rudrā does not indicate the vedic god Rudra, but his sons Maruts.
Maruts are known to move alongwith Indra and thus, the rishi is
calling maruts to come along with Indra, as their chief.
Edited
As per the OP's request, the translation of remaining 11 mantras from the same Hymn and from the same source, has been posted.
The tracker [=Agni?], stationed in front, has been smeared with the intentions of the great ones [=gods], he on whose doors father Manu
smeared insightful thoughts to the gods.
The stones with soma on their backs have sat up, as if to the measure of heaven. The solemn words and sacred formulations are now to
be recited.
Indra, knowing how, uncovered the cows for the Aṅgirases. That manly act of his is to be praised.
As of old, let Indra, strengthener of poets, fortifier of speech, the kindly one, come among us for help at the pouring of our chant.
And therefore, following the intention of your will, those eager to sacrifice (have cried out) “hail!”; their chants have cried out to
(you), who are swollen with strength, Indra, to give of the cowpen.
All heroic deeds, both done and to be done, are in Indra, whom the chants know as the very ceremony itself.
When cries were sent surging to Indra by the clan belonging to the Five Peoples, through the power of their inspiration, through the
power of his measure he laid the strangers low. He is peaceful
dwelling.
Here is the praise that follows you: you did these manly deeds; you furthered the turning of the wheel.
(Viṣṇu) strode widely to the rice porridge for this bull to live on. (Indra) took it, as cattle do barley.
Seeking help as we present this (praise hymn), through you (all) might we have skill as our father for the strengthening of the one
accompanied by the Maruts [=Indra].
Yes indeed! through our chanters we cry out again and again for your establishment according to the ritual sequence, o champion. Let
us conquer with you as our yokemate, Indra.
