I’m not sure what this notation (dots under notes)means exactly. I am practicing both pieces for an audition to enter orchestra. Help would be greatly appreciated. Also, if you would like to let me know anything else about this piece, as I am quite a beginner, please do let me know. Thank you. The piece is Symphony No. 15 in G Major and Appalachian Festival.
The dot under a note generally speaking means cut the note off short - often to around half its value. It doesn't mean the next note will be played any sooner, just that the note in question is truncated. This could even have been written as a shorter note, with a corresponding rest after, but it's simpler to merely write a staccato dot instead. The length is affected by approximately half, but is usually left to the discretion of the player.