Akademik

Х-38
ХЛЕБ ДА (И) СОЛЫ ХЛЁБ-СОЛЫ all obs, now used as an imitation of peasants' old-fashioned speech formula phrase these forms only fixed WO
1. a greeting, salutation to those who are seated around the table at a meal
good appetite!
enjoy your meal!
В дворницкую вошёл Юрий Андреевич с двумя вёдрами. «Хлеб да соль». - «Просим вашей милости. Садись, гостем будешь» (Пастернак 1). Yurii Andreievich came in with two buckets. "Good appetite." "Make yourself at home. Sit down and have dinner with us" (1a).
2. an invitation to a person or persons who arrive at mealtime and find another or others at the table, eating
you're welcome to join me (us)
please join me (us).
See X-40.

Большой русско-английский фразеологический словарь. — М.: ACT-ПРЕСС КНИГА. . 2004.