We all had to start somewhere with Brushless (with Brushed too, way back when😁).
It's not rocket science and has been discussed frequently on the site.
Brushless type numbers have 4 basic digits XXYY where XX is the diameter in mm and YY the motor body length in mm. Then a kV number. This is the number of rpm (off load!) per Volt applied. In general; Lower kV number means a slower revving higher torque motor, higher kV a faster revving high speed and lower torque motor.
So as 'Rule of Thumb'; short fat low kV for tug towing, longer thinner high kV for fast planing hulls.😉
Different manufacturers add extra number numbers or letters to designate a particular motor series or maybe max power in watts.
Then there's Inrunner and Outrunner!
The jury is still out on which is best for model boats😉
The Inrunner is easier to mount and cool cos you can treat it just like a brushed motor.
As the name implies with an Outrunner the outer casing spins round a fixed core, meaning it can only be mounted and cooled through the end mounting plate.
My personal opinion is that, unless you are building a fast Offshore Power Boat racer or Hydroplane racer, for high speed, high current short duration racing Inrunners are best left to the fly-boys.
With the right choice of kV, prop size (roughly same as motor diameter) and battery voltage I have never needed to cool my Outrunners.😉
Weight is also often a factor in smaller models. With a brushless you get 'More Oomph per Ounce'.😀
Don't forget that even with brushed motors there are various types with the same basic number (can size). But different performance depending on how the armature is wound!
E.g. there are 540s ranging from about 5000rpm torquey to 22000 or more rpm screamers!!
Read the specs before you buy!!
Whatever motor type you fit don't forget to put a fuse in line with the ESC + supply wire.
Fuse rating at least 10-20% less than the stall current of the motor or the max continuous current of the ESC. Otherwise: 🚤🔥😭
That's the simple basics for beginners, as I also was with brushless 3 years ago.
Hope this helps demystify a little.
Cheers, Doug 😎