Bu ikisi yan yana duruyor. - These two are standing abreast.
Üçü yan yana yürüyorlardı. - They were walking three abreast.
Английский Язык - Английский Язык
Определение abreast of в Английский Язык Английский Язык словарь
being up to particular standard or level especially in being up to date in knowledge; "kept abreast of the latest developments"; "constant revision keeps the book au courant"; "always au fait on the latest events"; "up on the news"
If people or things walk or move abreast, they are next to each other, side by side, and facing in the same direction. The steep pavement was too narrow for them to walk abreast