In plain words
For renunciants who are free from desire and anger, whose minds are disciplined and who know Ātma, Brahma-nirvāṇa is present both in this life and after it.
Word for word
For the renouncers freed from desire and anger, whose minds are controlled, who have known the Self, Brahma-nirvāṇa is both ways.
The commentators
Bhagavadgītābhāṣyam
किञ्च —
कामक्रोधवियुक्तानां कामश्च क्रोधश्च कामक्रोधौ ताभ्यां वियुक्तानां यतीनां संन्यासिनां यतचेतसां संयतान्तःकरणानाम् अभितः उभयतः जीवतां मृतानां च ब्रह्मनिर्वाणं मोक्षो वर्तते विदितात्मनां विदितः ज्ञातः आत्मा येषां ते विदितात्मानः तेषां विदितात्मनां सम्यग्दर्शिनामित्यर्थः ॥ २६ ॥
In plain words
And there is more —
'Free from desire and anger' means free of both together. 'Ascetics' means renunciants. 'Of controlled mind' means with the inner faculty held firmly in check. 'On both sides' means both while living and after death — the extinction that is Brahman, liberation, is already theirs, these people 'whose self is known.' Whoever has come to know their own self, understood it fully, is one 'whose self is known' — someone who sees things rightly. That's the meaning.
Close to the Sanskrit
And what more —
'Of those free from desire and anger' — desire and anger [together are] 'desire-and-anger'; free from those two; 'of ascetics,' [i.e.] renunciants; 'of controlled mind,' [i.e.] of restrained inner faculty — 'on both sides,' [i.e.] both of the living and of the dead, 'the extinction that is Brahman,' [i.e.] liberation, 'obtains for those whose self is known' — [i.e.] the self is known, understood, by whom, they are 'those whose self is known'; for them, those whose self is known, [i.e.] those who see rightly. That is the meaning.