跌跌撞撞 is an AABB reduplicated form. 跌 means 'to fall/trip' and 撞 means 'to bump/collide'. The AABB reduplication intensifies and vividly describes the manner — lurching from trip to bump repeatedly. It functions as an adverb before 地.
usage
Can be used literally (drunk/injured walking) or figuratively (a business stumbling through difficulties, e.g. 公司跌跌撞撞走到了今天).