It suspends ranked choice voting in both 2018 and 2020, and repeals it effective 2021 if the Maine State Constitution doesn't get changed by then to permit ranked choice voting in general elections for state office. The procedure to change the Maine constitution starts with a two-thirds vote of the legislature.
The House initially passed a version of the bill that would have allowed ranked choice voting to be used for primaries, and for congressional elections, in 2018. But the Senate amended it to suspend ranked choice voting. Finally, after many votes, the House agreed to the Senate version. Here is the Senate roll call. Generally Democrats voted in favor of ranked choice voting and Republicans voted against it. The Senate vote was 19-16.