Ngl your trainer is ass if that is the split he comes up with? you don't train back and shoulders?
you can learn most of this for free and from better source than your trainer, here is a headstart
For 4 days a good split would be
Day1 Chest+Back+arms
Day2 Legs+shoulder+abs
pick 1 compound and 1 isolated exercise for each muscle group
for example
Day1
Chest press(dumbell/barbell)
Lat pulldown
Chest flys(cable better but dumbell are also fine)
Rows( bendover rows/cable rows/facepulls or anyother horizontal pull movement)
overhead extension/cable pushdown( alternate between the two as they target different heads of tricep)
Curls(any kind works)
Day 2
Squats
Overhead press
RDL/seated leg curls
Lateral raises( cable/dumbell)
calf raises
cable crunch/leg raises
do 3 sets of each (or 2 sets if you can train till faliure)
rep range of anything btw 6-20 works if you are actually pushing your self to faliure or close to it(RPE of 8-10)
More things to Learn
Perfect technique and form for every movement you do
Mind muscle connection
Progressive overload
RPE
Nutrition(surplus, maingain and macros are enough)
dont fall for the supplement crap:
only 2 supplement actually have evidence: creatine and caffiene so dont waste your money on anything else
Some of my favourite youtuber would be
jeff nippard
will tennyson
greg douchette(if you like slop)( he is a snake oil merchant, so dont fall for his supplements but the other info he gives is solid)