The person who is directly in front of you in a line, queue, or in traffic.
example
An der Supermarktkasse hatte mein Vordermann einen übervollen Einkaufswagen.
At the supermarket checkout, the person in front of me had an overflowing shopping cart.
Usage tips
Word composition
The word 'Vordermann' is made up of 'vorder-' (a form of 'vor' (in front of)) and 'Mann' (man). So it literally describes the person who is at the front or standing in front of you.
EXAMPLE
Im Stau bewegte sich mein Vordermann plötzlich nicht mehr.
In the traffic jam, the person in front of me suddenly stopped moving.
Fixed expression
The expression 'jemanden oder etwas auf Vordermann bringen' is very common. It means to motivate a person to perform better or to get something back into a good, orderly condition.
EXAMPLE
Nach dem Winter muss ich den Garten erst einmal wieder auf Vordermann bringen.
After the winter, I first have to get the garden back into shape.
Gender-neutral use
Although the word contains 'Mann' (man), 'Vordermann' is used in everyday German for any person who is in front of you, regardless of gender. So the person can also be a woman.
EXAMPLE
Meine Vordermännin an der Kasse hat sehr lange gebraucht.
The woman in front of me at the checkout took a very long time.