What is the meaning of Trzeba?

it is needed, ought to

it is needed

one ought to

expresses the goodness of the following verb; it is needed, one ought to [with infinitive]

expresses the naturalness or obviousness of the following verb; ought to, must [with infinitive]

expresses the necessity or obligation of the following verb; it is needed, one ought to [with dative ‘for whom’; in addition, with infinitive ‘to do something’; or with genitive ‘what is needed’]

it is needed

Source: wiktionary.org