I was stacking wood when a yellowish liquid got on my hand i washed it off with soap and now there yellowish brown spot on my palm and thumb?

Wash well: As long as you have washed it throughly under running water for 10 min I would just watch it. If it is a dye or some sort of organic pigment it may stain your hands but if there is no burning, itching , or increasing redness it will go away in a few days. If it blisters or starts to spread see your doctor.

?sap: I suspect that this staining was from sap from the tree wood. If no further or spreading discoloration occurs, the stain will slowly fade over time. If any skin eruption does occur have it examined by a physician.