Learn Swedish: Det är ett svårt dilemma, men du borde inte ignorera det psykiska. - It is a difficult dilemma, but you should not ignore the mental part.

This is an example of substantivation, where an adjective acts as a noun to represent an abstract concept. By combining the neuter definite article det with the definite adjective form psykiska (which ends in -a), Swedish creates a phrase meaning 'the psychological aspect' or 'that which is mental' without needing to add an extra noun.

Could I say den psykiska delen instead of det psykiska?

Yes, den psykiska delen (the mental part) is grammatically correct and means the same thing. However, using det psykiska as a standalone abstract concept is a very natural and elegant way that native Swedish speakers express these broad categories.

Why does the adjective svårt have a -t at the end?

The noun dilemma is an ett-word in Swedish (ett dilemma). Because the phrase is indefinite ('a difficult dilemma'), the adjective svår must take the neuter agreement ending -t to become svårt.

Why use borde here instead of ska for 'should'?

borde is used to give advice or a recommendation, translating to 'ought to' or 'should'. If you used ska, it would sound much stronger and more rigid, like a command or a definitive future statement ('you shall not ignore').