There is no 20-lempira banknote** issued by the Banco Central de Honduras. The current Honduran lempira (HNL) series includes the following denominations:
The original answer stating "no 20 lempira bill" was incorrect. The L20 note exists and circulates widely. It features Dionisio de Herrera (first head of state of Honduras) on the obverse and the Presidential Palace on the reverse.
As of 2024: 1 USD ≈ 24.5–25 HNL. So L20 ≈ $0.80–$0.82 USD.
Older series (pre-2012) may have different designs but same denominations. Commemorative issues exist. For numismatic value, consult a dealer—most circulating notes trade at face value.