Below I have provided solutions for a few MS Flow syntaxes.
  1. //Multiple AND condition
  2. @and(equals(triggerBody()?['Status']?['Value'], 'Approve'),equals(triggerBody()?['Stage']?['Value'], 'Stage-1'))
  3. //Multiple OR condition
  4. @or(not(equals(variables('var1'), '')),or(not(equals(variables('var2'), '')),or(not(equals(variables('var3'), '')),not(equals(variables('var4'), '')))))
  5. //Check null values
To check null values, we can tsimply ype NULL under Expression in dynamic values.

Microsoft Flow Basic Operations
  1. //Date formatting
Add Compose from the action, and type the below syntax under Expression.
  1. formatDateTime(convertFromUtc(triggerBody()?['Start_x0020_Date'],'Eastern Standard Time'), 'MM/dd/yyyy hh:mm:ss tt')
Here ‘tt’ value from the above expression will provide you with the AM/PM value,
Microsoft Flow Basic Operations

Apply to each for multiple users,
  1. It can be useful when we want to iterate from the collection of records. Suppose I want to iterate over a collection of People Picker fields split by a semi-colon which I want to use for sending email.

  2. Initialize new variable as ‘UserColl’ at the start of Flow. Under Apply to each loop, add compose action, and under Expression type ‘concat(items('Apply_to_each')?['UsersColl'],';',variables('UserColl'))’

  3. Add Set variable from action set and under name select the variable we created above under Value Type Output from dynamic content.

    Microsoft Flow Basic Operations
Cheers!!