The US State Department considers Afrikaans, Dutch, French, Haitian Creole, Italian, Norwegian, Romanian, Spanish and Swedish to be the easiest to learn because they closely cognate with English. They are denominated “world languages.”
Albanian, Hindi, Hungarian, Polish, Turkish and Ukrainian, among others, are considered “hard languages” because of their significant linguistic and cultural differences from English.
Arabic, Chinese, Japanese and Korean are “super hard languages.”
Curiously, there is a separate category called “other languages” that includes German, Indonesian, Malay and Swahili. These are considered harder than French or Swedish but easier than Hindi or Polish.
I don’t know much about Swedish but I wonder why it’s considered so much easier for an English speaker than German. Also, I don’t get why Spanish or Romanian and more linguistically and culturally related to English than German.