This is the 204th most frequent Norwegian word.
stort
"Stort" means "big" or "large" in English.
Here, 'stort' is used as an adjective in its neuter singular form to describe a neuter noun 'huset' (the house).
Huset er stort.
The house is large.
In this case, 'stort' is used in a similar manner as an adjective, but it precedes the neuter indefinite singular noun 'problem' (problem).
Det er et stort problem.
It is a big problem.
Here, 'stort' again serves as an adjective describing 'steg' (neuter singular) in the context of metaphorical progression.