This really needs drawings:

Furan: https://pubchem.ncbi.nlm.nih.gov/compound/Furan (Note the Oxygen at the bottom of the ring)

N-propylpyrrole: https://pubchem.ncbi.nlm.nih.gov/compound/1H-Pyrrole_-1-prop...

The O (at the bottom) is replaced by N-CH2-CH2-CH3 (at the right) (the H are not drawn in the pictures).

This is above my chemistry level, but I'm surprised the cycle is close after the replacement. I'd be less surprised if the O to N-? were done in a non cyclic molecule or if the cycle is destroyed and opened.