A note is a sound or tone having two aspects:
1) The primary, auditory one, is pitch. Each note has a unique pitch, with a sound wave frequency measurable in hertz. In many parts of the world instruments are tuned to A at 440Hz.
2) The secondary, temporal one, is duration, called “time value” or “note value”. When written or played each note has a specific duration, how long it lasts relative to the beat.
The note A at 440Hz, with duration of 4 beats:
In terms of melody, when pitch and duration are combined there is identifiable melodic shape and melodic rhythm. Pitch permits the creation of melody; a succession of notes gives melody direction: the melodic shape. Duration creates melodic rhythm.
The way the notes are played and connected to one another: anywhere from gently played to heavily attacked; held for the full duration of the note value or clipped short; smoothly connected to the notes before and after, or continuously separated.
There are many technical terms for these differences, but for tango we mostly need to be aware of two broad kinds of articulation, the extreme ends of the spectrum: a connected legato, which often creates a lyrical quality, and an accented, clipped short marcato. Generally, the strings and singers have a legato articulation, while the bandoneons have a marcato one.
Dynamics is the volume factor in music. There are two broad categories: a relative volume level which does not change until some marking specifies it does; and a volume that changes gradually or suddenly.