Here the original manuscript has an ampersand at the end of the line, but when copying into the printer’s manuscript Oliver Cowdery accidentally missed this final word in a line of 𝓞. Oliver sometimes omitted small words at the ends of lines in his copywork; for some other examples, see the list under Alma 11:21.
As noted under Alma 40:3, there are 22 instances of and now in the original text for Alma’s discourse with Corianton (Alma 39–42). There is nothing wrong with the and here in Alma 40:6; the critical text will restore it.
Summary: Restore the and at the beginning of Alma 40:6; as he copied the text from 𝓞 into 𝓟, Oliver Cowdery accidentally skipped the ampersand that occurred here at the end of a line in 𝓞.