Electric field lines are a graphical representation of the electric field near
a configuration of charge.
Here is the vector field diagram for the electric field around a dipole
and here is the corresponding electric field lines diagram.
Finally for another example, here are the field lines for two positive
charges.
The field lines diagram are not just qualitative, the density of field lines
measure the strength of the electric field (and indicates the direction).
The number of field lines emanating from a charge is a measure of how strong
that charge is. Here both point charges have equal number of lines going out
of them. They have to be to equal charges.
Check your understanding