I am very new to writing apex code and have come to a roadblock when it comes to moving the updated Visualforce page I've helped edit out of the sandbox and into production. When I created the changeset I added the visual force page and associate apex class that I've been working in. When I went to validate this change set in production I got several component errors. Namely that a certain variable doesn't exist and that the apex class I thought I'd created didn't exist as well.

Below I've attached the code where several of the errors exist namely that the Variable: Special_Skills__c doesn't exist. I have done some trailheads and googled other questions to get to the point where the visualforce page created is exactly what we are looking for. I just need some help in overcoming these errors so that I can get this into production ASAP in addition to increasing my knowledge of code and working in a sandbox and ultimately transferring this information into production. Thanks in advance!

//get the multi-select pick list values
    public List<SelectOption> MPOptions3 {
     get {
       List<SelectOption> options = new List<SelectOption>();
       
       DescribeFieldResult SpecialSkills = Schema.account.Special_Skills__c.getDescribe();  
     
       List<Schema.PicklistEntry> f = SpecialSkills.getPicklistValues();
       Integer listSize = f.size();
         
       for(Schema.PicklistEntry a : f) {
           options.add(new SelectOption(a.getValue(), a.getLabel()));
        } 
       return options;
     }  
     set;
    }

    
    //get and set the multi-select pick list as checkboxes
       public String[] MPItems3 { 
     get {
        String[] selected = new List<String>();
        List<SelectOption> sos = this.MPOptions;
        for(SelectOption s : sos) {
        if (this.account.Special_Skills__c !=null && this.account.Special_Skills__c.contains(s.getValue()))
           selected.add(s.getValue());
        }
        return selected;
     }public set {
        String selectedCheckBox = '';
        for(String s : value) {
         if (selectedCheckBox == '') 
           selectedCheckBox += s;
         else selectedCheckBox += ';' + s;
        }
        account.Special_Skills__c = selectedCheckBox;
     }
   }