Just to state the absolutely obvious.
Pitch: The frequency of the sound wave. Same letter pitches imply a power of 2 relation between them. So to compute the physical frequency f you'd calculate:
f = base_frenquency* 2^(Octave)
.
So the A above middle C, on a piano, is 440Hz and if you'd want to have 2 octaves above that then it's
440Hz*2²=440Hz*4= 1760Hz
.
Or if you want the 3 octaves below that than it's
440Hz*2^(-3)= 440Hz *1/(2³) = 440Hz *1/8 55Hz
.
So if you have a frequency value for one of the note names (those can be looked up) and can figure out how man octaves are between that and your note, then you can compute the physical frequency or vice versa.
Though that is the physics point of view, a musician is usually fine with frequencies being obfuscated by letters. They are mostly interested in the note names as their relative distance creates melody (played sequentially) or harmony (played parallel). And the octave is relevant for a musician in terms of whether it's within the range of their instrument and how the fingers and/or air stream have to be manipulated to achieve that sound.
The duration: Is ... well the duration of how long you hold the note. It's usually indicated by a combination of the a relative time scale like the note length idk quarter, half, full, eights and so on. AND with an absolute descriptor telling you idk that you play idk 120 quater notes per minute or something like that, could also be that it's just implied with a vague word like "vivid" or "grave" or whatnot indicated it should be played fast or slow but left to you what exactly that means (there are also tables that give a rough estimate). Or if your program is more technical it could be a literal time duration in seconds or milliseconds.
So you can use the name+octave to infer the frequency from it but you'd need to find a different place to make use of the duration information as that is apparently not handled at the note object.