When a dot is placed next to a note, it increases its duration by half.
Dotted Half Note: A half note (2 beats) with a dot after it becomes a dotted half note. The dot adds an extra half of its original value, extending its duration by 1 beat. Therefore, a dotted half note is held for 3 beats.

Dotted Quarter Note: A quarter note (1 beat) with a dot after it becomes a dotted quarter note. The dot adds half of its original value, extending its duration by 0.5 beats. So, a dotted quarter note is held for 1.5 beats.
Dotted Eighth Note: An eighth note (0.5 beats) with a dot after it becomes a dotted eighth note. The dot adds half of its original value, extending its duration by 0.25 beats. Therefore, a dotted eighth note is held for 0.75 beats.

NB
When Two Dots are placed after a note it is called a doubly-dotted note, and its length is increased by Three-quarters, the second dot adding half the value of the first dot to the note, Thus a doubly-dotted Minim,

Dotted notes are useful for creating rhythmic variations and syncopated patterns in music. They allow for subtle rhythmic accents and add interest to the overall rhythm. When encountering a dotted note, it’s important to count the original note value and add half of its value to determine its total duration.
Practicing dotted notes helps improve rhythmic precision and develops a sense of timing. It’s beneficial to practice playing or singing patterns that include dotted notes to become comfortable with their durations and incorporate them smoothly into musical performances.