Samson was not travelling alone, he was being led by the men who had tied him with ropes. AT: "When they came" (See: [[rc://en/ta/man/translate/figs-explicit]])
The phrase "came on" means that Yahweh's Spirit influenced Samson. In this case, he made him very strong. AT: "made Samson very strong" (See: [[rc://en/ta/man/translate/figs-idiom]])
Samson easily broken the ropes that bound his hands. The author describes how easily he broke the ropes by saying it was as if they had become burnt flax. AT: "He snapped the ropes on his arms as easily as if they had been stalks of burned flax" (See: [[rc://en/ta/man/translate/figs-simile]])