To move all code from Trigger to Apex Classes(Handler Classes) is one of the Salesforce Best Practices. Here is an example to write Trigger Handler class.

Apex Trigger:

trigger objectTrigger on Object (before insert, before update, before delete, after insert, after update, after delete, after undelete) {
    
    objectTriggerHandler handler = new objectTriggerHandler();
    
    //Before Insert
    if(Trigger.isInsert && Trigger.isBefore){
        handler.OnBeforeInsert(Trigger.new);
    }
    //After Insert
    else if(Trigger.isInsert && Trigger.isAfter){
        handler.OnAfterInsert(Trigger.new);
    }
    //Before Update
    else if(Trigger.isUpdate && Trigger.isBefore){
        handler.OnBeforeUpdate(Trigger.old, Trigger.new, Trigger.newMap);
    }
    //After Update
    else if(Trigger.isUpdate && Trigger.isAfter){
        handler.OnAfterUpdate(Trigger.old, Trigger.new, Trigger.newMap);
    }
    //Before Delete
    else if(Trigger.isDelete && Trigger.isBefore){
        handler.OnBeforeDelete(Trigger.old, Trigger.oldMap);
    }
    //After Delete
    else if(Trigger.isDelete && Trigger.isAfter){
        handler.OnAfterDelete(Trigger.old, Trigger.oldMap);
    }
    //After Undelete
    else if(Trigger.isUnDelete){
        handler.OnUndelete(Trigger.new);
    }
}

Trigger Handler Apex Class:

public with sharing class ObjectTriggerHandler {
    
    private boolean isExecuting = false;
    
    public ObjectTriggerHandler(boolean isExecuting){
        this.isExecuting = isExecuting;
    }
    
    public void OnBeforeInsert(List<Object> newObjects){
        //EXECUTE BEFORE INSERT LOGIC
    }
    
    public void OnAfterInsert(List<Object> newObjects){
        //EXECUTE AFTER INSERT LOGIC
    }
    
    public void OnBeforeUpdate(List<Object> oldObjects, List<Object> updatedObjects, Map<Id, Object> ObjectMap){
        //BEFORE UPDATE LOGIC
    }
    
    public void OnAfterUpdate(List<Object> oldObjects, List<Object> updatedObjects, Map<Id, Object> ObjectMap){
        //AFTER UPDATE LOGIC
    }
    
    public void OnBeforeDelete(List<Object> ObjectsToDelete, Map<Id, Object> ObjectMap){
        //BEFORE DELETE LOGIC
    }
    
    public void OnAfterDelete(List<Object> deletedObjects, Map<Id, Object> ObjectMap){
        //AFTER DELETE LOGIC
    }
    
    public void OnUndelete(List<Object> restoredObjects){
        //AFTER UNDELETE LOGIC
    }
    
    public boolean IsTriggerContext{
        get{ return isExecuting;}
    }
}