In plain words
But the fruit gained by people of limited understanding is finite. Worshippers of the devas go to the devas; My devotees come to Me.
Word for word
But finite is that fruit of those of small understanding; the worshippers of the devas go to the devas, My devotees go to Me too.
The commentators
Bhagavadgītābhāṣyam
यस्मात् अन्तवत्साधनव्यापारा अविवेकिनः कामिनश्च ते, अतः —
अन्तवत् विनाशि तु फलं तेषां तत् भवति अल्पमेधसां अल्पप्रज्ञानाम् । देवान्देवयजो यान्ति देवान् यजन्त इति देवयजः, ते देवान् यान्ति, मद्भक्ता यान्ति मामपि । एवं समाने अपि आयासे मामेव न प्रपद्यन्ते अनन्तफलाय, अहो खलु कष्टं वर्तन्ते, इत्यनुक्रोशं दर्शयति भगवान् ॥ २३ ॥
In plain words
Since the means they work with all come to an end, and since they have no viveka and are driven by desire — therefore:
That fruit has an end — it perishes, and only those of little intelligence, little real wisdom, settle for it. Worshipers of the gods go to the gods; my own devotees come to me. And notice this: the effort on both sides is exactly the same, yet one group never turns to me alone, and so misses out on a fruit that has no end at all. What a shame, truly — that's genuinely unfortunate for them. And in saying this, the Blessed Lord is showing nothing less than his own compassion.
Close to the Sanskrit
Since they are ones whose engagements are with means that have an end, and are without discrimination and full of desire, therefore —
Having an end, perishable, but, is the fruit of those of little intelligence, of little wisdom. Worshipers of the gods — those who worship the gods, thus, worshipers of the gods — they go to the gods; my devotees go to me as well. Thus, even though the effort is equal, they do not take refuge in me alone, for the sake of unending fruit — alas, how truly unfortunate is their standing — by saying this, the Blessed Lord shows [his] compassion.