один в поле не воин

1) General subject: there is safety in numbers, one cannot conquer alone

2) Set phrase: no man is an island, one man can't do the work of ten, one man does not make a team (contrast: many hands make light work. one man is worth a hundred and a hundred is not worth one), one man in the field is no warrior, one man no man (he who works or fights alone, cannot do much (cannot cope with the task)), one man, no man (дословно: Один человек не в счёт), the voice of one man is the voice of no one, the voice of one man is the voice of no one (дословно: Голос одного человека не в счёт), one body is nobody, one's as good as none

3) Phraseological unit: one soldier does not make a battle