This involves the duration of the notes. The so-called duration, in layman's terms, is the length of sound. Commonly used time values are as follows:
Full note: add three bars after a note. Sing four beats with quarter notes as one beat;
Binary note: add a small bar after the note. Sing two beats as one beat with quarter notes;
Quarter note: A note has no bars. Sing a beat with quarter notes as a beat;
Octave note: add a small bar under the note. Sing half a beat with quarter notes as a beat;
Sixteenth note: add two bars under a note. Sing 1/4 beats with quarter notes as a beat;
Thirty notes: add three bars under one note. Sing 1/8 in a quarter note;
……
The remaining two bars, if they are quarter notes, will stop a quarter beat.
The second question:
This is a smooth line, which has three purposes:
1 Used on the same note, the one above you. Two connected notes sing only one note, but the length is the sum of the lengths of the two notes. The two notes here, the upper two high notes 2 and the lower two high notes 5, only play one note, and the time value should add up to 1/4+3/4= 1.
Used for several different sounds. There is a lyric below, which sings several sounds below this arc.
In instrumental music, the notes below this line should be played smoothly and coherently. Bowstring instruments are played in a bow.