The label of your drawing is: 1, and the small red flag indicates on-site welding; 2.6V is single-sided V-shaped welding groove is 6; 3, 4δ is the side length of fillet weld 4; 4. < 2 at the tail indicates resistance welding.

For a more detailed explanation, I suggest you look at GB/T324-2008 weld symbol representation. pdf。