Of course! Although this could become a really long answer, I'll try to make it as short as I can.
First of all, as you might already have figured out, the symbol V is the Roman number for 5. (IV is 4, VI is 6, VII is 7 and VIII is 8)
When naming chords, we can separate two main techniques of naming them.
The first is when we do a so called "chord" analysis. Then we name the chords simply for what they are by themselves, alone.
Like Gm for a G minor chord, or C7 for a C major 7th chord. In this simple chord analysis we don't use the Latin numbers.
The second is called "functional analysis" and is used usually in music theory (Harmony) when we analyze chords in a context.
This means how they stand in relation to other chords. And this is where the roman numerals are handy!
Each step on a scale is represented by a roman numeral, this is called scale degree.
So, in the scale of C major, the first step is I, the fourth step is IV, the fifth step is V, and so on. If we build triads on each of the steps in the scale, they can also be named I, IV, V and so on.
So when doing a "functional" analysis of a score (as you would do in music theory class) you'd use roman numerals representing the chords from the scale of the key the piece is in. This is called Diatonic Harmony.
But, since this is a very useful way of "naming" chords (assuming you know the key) it's often used by all types of musicians in naming chord progressions.
By using for example the chord progression C-F-G-C you can instead use I-IV-V-I (in the key of C major). Then, if you decide to change the key to, let's say A major, you can still use the same numerals but in the key of A. No need to re-write the score!
Enjoyed your piece on practicing a new song by breaking it down into small sections and then practicing each section or part in a random order. I’m wondering
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