Allah says in the Qu'ran:
وَقُل لِّلْمُؤْمِنَاتِ يَغْضُضْنَ مِنْ أَبْصَارِهِنَّ وَيَحْفَظْنَ فُرُوجَهُنَّ وَلَا يُبْدِينَ زِينَتَهُنَّ إِلَّا مَا ظَهَرَ مِنْهَا وَلْيَضْرِبْنَ بِخُمُرِهِنَّ عَلَىٰ جُيُوبِهِنَّ وَلَا يُبْدِينَ زِينَتَهُنَّ إِلَّا لِبُعُولَتِهِنَّ أَوْ آبَائِهِنَّ أَوْ آبَاءِ بُعُولَتِهِنَّ أَوْ أَبْنَائِهِنَّ أَوْ أَبْنَاءِ بُعُولَتِهِنَّ أَوْ إِخْوَانِهِنَّ أَوْ بَنِي إِخْوَانِهِنَّ أَوْ بَنِي أَخَوَاتِهِنَّ أَوْ نِسَائِهِنَّ أَوْ مَا مَلَكَتْ أَيْمَانُهُنَّ أَوِ التَّابِعِينَ غَيْرِ أُولِي الْإِرْبَةِ مِنَ الرِّجَالِ أَوِ الطِّفْلِ الَّذِينَ لَمْ يَظْهَرُوا عَلَىٰ عَوْرَاتِ النِّسَاءِ وَلَا يَضْرِبْنَ بِأَرْجُلِهِنَّ لِيُعْلَمَ مَا يُخْفِينَ مِن زِينَتِهِنَّ وَتُوبُوا إِلَى اللَّهِ جَمِيعًا أَيُّهَ الْمُؤْمِنُونَ لَعَلَّكُمْ تُفْلِحُونَ
And say to the believing women (that) they should lower [of] their gaze and they should guard their chastity, and not (to) display their adornment except what is apparent of it. And let them their head covers over their bosoms, and not (to) display their adornment except to their husbands, or their fathers or fathers (of) their husbands or their sons or sons (of) their husbands or their brothers or sons (of) their brothers or sons (of) their sisters, or their women or what possess their right hands or the attendants having no physical desire among [the] men or [the] children who (are) not aware of private aspects (of) the women. And not let them their feet to make known what they conceal of their adornment. And turn to Allah altogether O believers! So that you may succeed.
From Tafsir Maududi:
The literal translation of the Text would be: "those from among the men who are your subordinates and have no desire." The obvious meaning is that apart from the mahram males, a Muslim woman can display her adornment only before the man who satisfies two conditions: firstly, he should be in a subordinate capacity, and secondly, he should be free from sexual urges either due to advanced age, impotence, mental weakness, poverty or low social position, so that he cannot cherish the desire or have the boldness to think evilly of his master's wife, daughter, sister or mother. Anybody who studies this injunction in the right spirit with a view to obeying it, and not for the sake of finding ways and means of escaping from or violating it, will readily appreciate that the bearers, cooks, chauffeurs and other grown up servants employed these days in the houses do not fall in this category. The following clarifications given by the commentators and the jurists of this point would show the type of men envisaged in the verse:
Ibn 'Abbas: This implies a man who is a mere simpleton and has no interest in women.
Qatadah: A poor man who is attached to you merely for his sustenance.
Mujahid: A fool who only needs food and has no desire for women.
Sha'bi: The one who is a subordinate; entirely dependent on his master, and cannot have the boldness to cast an evil look at the womenfolk of the house.
lbn Zaid: The one who remains attached to a family for such a long time that he is regarded as a member brought up in that house, and who has no desire for the women of the house. He is there merely because he gets his sustenance from the family.
Ta'us & Zuhri: An idiot who does not cherish the desire for the women nor has the courage to do so.
(Ibn Jarir, Vol. XVIII, pp. 95-96, Ibn Kathir, Vol. III, p. 285).
Therefore the verse refers to men who have no sexual desire or servants etc. Those who are interested in other stuff and not women. The other things it could be are listed above.
And Allah knows best.