the hymnal teaches me nothing about left hand.
That's where you're messing up. The hymnal should teach you what your LH note is for the chord. Hymns are basically chords that were written to be sung rather than played. If you can figure out the chord, you can play it anyway you want on the piano. The bottom, or bass voice will usually be your LH note for the chord. I suggest learning the progression of the chords first.
Rolling (arpeggiating) is where you play each note one at a time, but hold down each note as you play. So, using that Ab-Eb-Ab, you would play the first Ab, hold it, play the Eb, hold it as well, then the second Ab and hold it. It should be a fluid, kinda fast motion just like a chord arpeggio, but in the LH.
It also seems to me like you're struggle may be more rhythmic than necessarily learning notes and chords. Like, how to play quarter notes, sixteenth notes, etc. in the different time signatures. I've found that clapping the rhythms first helps with timing.
and what are some standard licks i can do.?
Here's a couple of things you can do. I'll stay with the key of Ab for examples:
You can throw a little RH run based on the pentatonic scale in between chords: #2, 3, 5, 6, 1 --> single notes: B, C, Eb, F, Ab octaves: B-B, C-C, Eb-Eb, F-F, Ab-Ab
A little 3-4-5-6-7-1 turnaround progression to get back to the beginning of the song:
3 / 1 chord (C / Eb-Ab-C)
4 / 2 or 4 chord (Db / F-Bb-Db)
5 / 1 chord (Eb / Eb-Ab-C)
6 / 4 chord (F / Db-F-Ab)
7 / 5 chord (G / Eb-G-Bb)
1 / 1 chord (Ab / Eb-Ab-C)