What is the meaning of Być?

to be, to exist

to be [with nominative or instrumental]

to be [with adjective]

in future tense, forms the compound future tense of imperfective verbs [with infinitive]

in present tense, forms the compound past tense [with past participle]

in past tense, forms the pluperfect tense [with past participle]

in aorist, forms the conditional mood [with past participle]

to be indicates sameness or membership in a class [with nominative or instrumental]

to be auxilary verb used for predication [with adjective]

in future tense, forms future tense of imperfective verbs [with infinitive or past-tense clause]

in past tense, forms pluperfect tense [with past-tense clause]

to be indicates location, there be

to be [with nominative or instrumental]

to be [with adjective]

in future tense, forms future tense of imperfective verbs [with infinitive or past-tense clause]

in past tense, forms pluperfect tense [with past-tense clause]

to be

forms compound past tense [with l-participle]

Source: wiktionary.org