John Gill Commentary Leviticus 23:27

"Howbeit on the tenth day of this seventh month is the day of atonement: it shall be a holy convocation unto you, and ye shall afflict your souls; and ye shall offer an offering made by fire unto Jehovah." — Leviticus 23:27 (ASV)

Also on the tenth [day] of this seventh month
Tisri, the same as before, answering to part of our September, and part of October:

[there shall be] a day of atonement ;
for all the sins of the year past; see (Leviticus 16:29Leviticus 16:30) ;

it shall be an holy convocation unto you :
when they should be called together for the exercise of holy duties:

and you shall afflict your souls ;
their souls, by repentance, contrition, and humiliation for sin, and their bodies by fasting; and, as the Targum of Jonathan paraphrases it,

``by abstaining from eating and drinking, and the advantage of bathing and wiping, and the use of the bed and sandals;'' hence called the fast, (Acts 27:9) ; (See Gill on Leviticus 16:29);

and offer an offering made by fire unto the Lord ;
a burnt offering, of which see (Numbers 29:8–11) .