Rashford scored his fourth England goal on his 26th cap against Spain in the UEFA Nations League on Saturday night but could not prevent the Three Lions from suffering a 2-1 defeat.
The 20-year-old has also made more than 120 appearances for United since breaking into their first team, and Henderson has paid tribute to the talent of his international teammate.
"We all know how talented Marcus is," Henderson told Sky Sports News. "His was a great finish. He had another one or two chances that maybe he would have liked to have scored but I thought he looked sharp.
"He was lively and he's always a threat on the counter-attack. He's a fantastic young player so he just needs to keep learning, keep improving. He's a big part of our team."
England will look to recover from three straight defeats when they face Switzerland on Tuesday night.