"横跨一步躲避" can be translated into English as "step aside (to dodge)" or "take a sidestep (to avoid)" .
Here are two example sentences:
He stepped aside to dodge the flying ball. （他横跨一步躲避飞来的球。）
She took a sidestep to avoid the oncoming obstacle. （她横跨一步躲避迎面而来的障碍物。）