How to record export transaction?

You will record $5000 at the rate which was prevailing on date of invoice say 50/$

Drs would be 5000 X 50

when you receive the payment or if you are closing your books then exchange fluctuation should be considered

Suppose the rate is 55 on date of payment

Bank 5000 X 55

TO drs 5000 X 50

To exchange diff(P&L) 5000 X 5

if you are closing the books and have not recevied the payment

Drs 5000 X (55-50)

to exchange difference 5000 X 5

all the relevant info is in AS-11

https://www.mca.gov.in/Ministry/notification/pdf/AS_11.pdf