Phrasing is something that cannot be precisely quantified. It can only be described by words like "legato" and "tenuto" and "staccato"
I tell my students to remember this: The music does not exist on the sheet of paper. The written sheet music is a detailed encoded message to help the musician figure out how to perform the music. The musician has to decode the messages and translate that into a live musical performance with instruments and voices.
Terms like "legato", "staccato", "tenuto" etc., and the use of the slurs, describe in words and pictures how to play a phrase of music.
Every note you play is going to have a starting point and a stopping point. If you play a series of notes (and this depends greatly on which instrument you are playing) there has got to be a tiny amount of silent space between most notes, or between some of the notes, when it becomes necessary to lift and reposition your fingers, or where you need to breathe air, or lift your bow or reverse your bow direction if you are playing violin, for example.
So you start out playing a phrase, a series of notes with no additional symbols to tell you how to connect them. You use the "default" phrasing that is appropriate to playing your particular instrument. For example, if you were playing a piano, and you examined the waveforms of an audio recording of your playing, you might find that you are holding each note for about 90% of the duration indicated by the note values. But this varies from note to note within the phrase. You need a small amount of empty space between each note to move your fingers and hand position.
The term "legato" means for you to try to connect the notes in such a way that they sound even more smooth and connected than the default. "Staccato" means to hold each note for approximately 50% of its notated value. And so forth.
These are all approximations, the "feel" of the phrasing. It's something you just learn through practice and through interacting with your music teacher and other musicians.