Change the days of the week to abbreviations

Instead of Monday, Tuesday, etc., you can have the Month View show the days of the week as the appropriate abbreviations (e.g. Mon., Tues., etc.). Here's an example:

KB - week abbrev

Perform a template override, by making a copy of '/wp-content/plugins/the-events-calendar/src/views/month/loop-grid.php' and place in the 'tribe-events/month' folder in your theme.

Look for the following line:

<th id="tribe-events-<?php echo esc_attr( strtolower( $day ) ); ?>" title="<?php echo esc_attr( $day ); ?>" data-day-abbr="<?php echo esc_attr( $wp_locale->get_weekday_abbrev( $day ) ); ?>"><?php echo $day ?></th>

Then replace that with this new code:

<?php $short_day = esc_attr( $wp_locale->get_weekday_abbrev( $day ) ); ?>
<th id="tribe-events-<?php echo esc_attr( strtolower( $day ) ) ?>" title="<?php echo $short_day ?>" data-day-abbr="<?php echo $short_day ?>"><?php echo $day ?></th>

The idea is to grab the short form of the weekday via WordPress's locale helpers, then use that in the table header (including the title attribute - though it may be preferred to use the full-length text here).