Along side at the same level (think of runners crossing a finishing line "breast to breast" they are abreast of each other and finish at the same time).
Being abreast means being side by side.
it means walking side to side
Abreast means beside one other with others in back or front. Riding no more than two abreast means no more than two riders across side by side in one seat, for all riders in the vehicle or method of transport. For example, no more than two abreast ona roller coaster means no more than two across in each row.
abreast - side by side The parade had six drummers marching abreast.
draw abreast = gleichziehen
We have been abreast of this situation for a time now.
The brass band passed by, marching four abreast.
The origin of abreast is late Middle English: from A- 'in' + breast.
I have information here to keep you abreast of the situation, sir.
The president wants to stay abreast of the most recent developments in Libya. OR The protest marchers walked arm-in-arm, five abreast down the street.