It is normally written as one word: halftyd.
This is very common in Afrikaans, where compounds are often written together:
English sometimes writes similar words as one word, two words, or hyphenated depending on the expression, but Afrikaans usually prefers the single compound form here.
A simple English-friendly approximation is:
HALF-tate or HALF-tide (depending on accent and how closely you want to imitate Afrikaans)
A few pronunciation notes:
If you are a beginner, saying something close to halftide will usually be understood.
Afrikaans often does not use an article in predicate expressions like this, just as English often does not.
Compare:
So halftyd here functions naturally without ’n or die.
No special capitalization is needed here. In normal Afrikaans:
So the standard spelling is:
Afrikaans does not capitalize ordinary nouns the way German does.