Electric current, A.K.A, "conventional current", is an abstract current, the flow of electric charge. From a previous answer I gave here:
Electric current is an abstract current, the flow of electric charge, not a physical current like, say, electron current, the flow of electrons.
But electric charge is a property of things, not a thing, i.e.,
electric charge is always "carried" by a thing.
So, while an electron current is necessarily an electric current (due
the negative electric charge carried by the electron), an electric
current is not necessarily an electron current.
For example, in a salt solution, we have two species of electrically
charged ions present, the positively charged sodium ion and the
negatively charged clorine ion. Imagine that the sodium ions are
moving to the right and the chlorine ions are moving to the left.
Obviously, we have two ion currents in opposite directions but there
is just one electric current and it must have a direction. The
direction of electric current is, by convention, the direction of the
flow of positive charge.
So, in this case, both ion currents contribute to an electric current
to the right. The first term is due to the positive ions to the
right. The second term is due to the negative ions to the left where
the negative sign numerically "flips" the contribution to the
Think about it this way, if I told you that I was travelling at -60mph
west, you'd know that I was actually going 60mph east. Similarly, a
negative charge current leftward is an electric current rightward.
It's a model we use to describe flow of charge. "All models are flawed but some are useful" - and this one is very useful.
It is true that the mobile charges in metals are electrons but it is not always the case. In other situations the mobile charges are positive ions.
Don't get hung up on this. You don't need to think about electrons for most electronic engineering. Just volts, amperes, watts, ohms, henries and farads will get you a long way.
Give Benjamin some capital letters - even if you think he got it backwards.