I came across a sentence and didn't really catch how it was made, like, in a grammatical sense. "Minulla taitaa olla flunssa".

See a translation

Think of "Minulla on flunssa". So it's "flunssa" that IS - "flunssa on" - even if in other languages you might say something like "I HAVE the flu".

Now, on to "taitaa olla" (= looks like there is, to translate it roughly). It is similar to "saattaa olla" (= might be).

There's an old song called "Taitaa tulla kesä". Tulla is to come and kesä is summer so the title means "It looks like summer is coming".

So "taitaa" is a very specific kind of verb, and it (in this case) means something that looks like it might be or something that is probable.

("Taitaa" can also mean to command or master a skill: hän taitaa viulunsoiton = he knows how to play the violin - but it's another meaning of the verb used in a different situation.)

Minulla taitaa olla flunssa = It looks like I have the flu, I might have the flu, I probably have the flu, etc.