The shortened 60-game schedule starts July 23rd, but with a few new rules. On the financial side of things, player salaries will be pro-rated for the shortened season. A player contracted to earn $1,000,000 with have that salary multiplied by (60/162) — dropping his 2020 earnings to about $370,000.
On the field, the first change you'll see is that the National League will be using the Designated Hitter this year. Major League Baseball claims this is a temporary change, but I'm skeptical.
The second change only affects extra inning games, where every half-inning after the 9th will start with a runner on second base. The traditionalist in me hates this rule, but I have to admit that it will have the desired effect: the average length of an extra-inning game will drop from 11.1 innings to 10.4 innings — with roughly 2/3rds of extra-inning games ending after just one extra frame.
The length of the average game dropped from 9.18 innings to 9.11 innings. This doesn't seem like much of a difference, but the rule change significantly reduces the number of games that go deep into extra innings. A team has about 15 extra-inning games in a typical 162-game season. Without this new rule, more than 25% of extra-inning games last 12 or more innings. With this rule, only 7% reach the 12th inning — and games of 14 or more innings are virtually unheard of (less than 0.03% of the total).