Question

how to undertand kvl

Answer 1

Its simple........ Sum of all the voltages in a loop is equal to zero!

Answer 2

If I am not wrong I believe this statement is correct :p

Answer 3

please try to think in this way: voltage is something similar to height. if you move a object along an arbitrary path that forms a loop, the sum of potential energy is zero.
you can consider voltage like that. actually the idea will be clearer if you learn something about graph theory since circuit is a special situation.

Answer 4

KVL - Kirchhoff's Voltage Law, the voltage sum around a closed loop, mesh, is zero, or the voltage supplied equals the voltage loss in a closed loop.
KCL - Kirchhoff's Current Law, the current sum into a node is zero, in positive, out negative.