This is the 590th most frequent Finnish word.
mielestään
"In their opinion" or "as they see it."
'Mielestään' is used to express 'in their opinion' here, indicating the subject's personal view.
Hän mielestään ansaitsi palkinnon.
In their opinion, they deserved the reward.
'Mielestään' is applied to 'them' to denote their shared viewpoint.
He mielestään löysivät parhaan ratkaisun.
In their collective opinion, they found the best solution.
Although 'mielestäni' (first person singular possessive suffix) is used, it demonstrates the functionality of the word in expressing personal opinions.