This is the 558th most frequent Russian word.
хотя
"Хотя" means "although" or "even though."
Here, "хотя" is used to introduce a contrasting clause, showing an opposition between being tired and continuing to work.
Хотя я устал, я продолжаю работать.
Although I am tired, I keep working.
Here, "хотя" in the form "хотя бы" changes its meaning to "at least," introducing a minimal condition or suggestion.
Хотя бы попробуй это сделать.
At least try to do this.
In this sentence, "хотя" serves to express a contrast between the action of going for a walk and the adverse condition of rain.