Hello, the rule is written as follows:
"When the spymaster reveals an obstacle to the spies they will play 1-2 card(s) from their hand of a matching suit."
This means the spymaster has two options when revealing an obstacle:
1 - Play a 1 card, which will only have one suit and one difficulty value.
2 - Play 2 cards, which must have the same suit to determine the challenge type and a difficulty value that will be the sum of the card's value.
I hope this clears up any confusion.