Setters and Getters in PHP are object methods used in OOP programming. The basis being you set a property to your value and then you can get it.

Using setters and getters has the advantage of being a clear and clean process, having validation and defined debugging along with greater flexibility.

Using OOP is subjective, from my limited use and obvious statements it is best used for large projects where the code will be shared and/or worked on by many.

Setters

The setters, set a value for a property:

<?php
class account //account class
{
    private $account_id;
    private $created;
    private $owner_id;
    private $balance;

    public function setAccount($account_id) //Setter
    {
        $this->accountId = $account_id;
    }

    public function setCreated($created) //Setter
    {
        $this->accountCreated = $created;
    }

    public function setOwner($owner_id) //Setter
    {
        $this->accountOwner = $owner_id;
    }

    public function setBalance($balance) //Setter
    {
        $this->accountBalance = $balance;
    }
    
}

Getters

The getters, get (return) what has been set:

public function getAccount(){ //Getter
    return $this->accountId;
}

public function getCreated(){ //Getter
    return $this->accountCreated;
}

public function getOwner(){ //Getter
    return $this->accountOwner;
}

public function getBalance(){ //Getter
    return $this->accountBalance;
}

These would be included in the class account.

Now to set and get, call and assign a new instance of the class account. Set the account as 12345 and then echo the set account.

$ac = new account();
$ac->setAccount(12345);
echo $ac->getAccount();//12345

To dig further:

$ac = new account();
$ac->setAccount(12345);
$ac->setOwner('Garry');
$ac->setBalance(455);
echo $ac->getAccount().' '.$ac->getOwner().' '.$ac->getBalance();//12345 Garry 455

Not seen above in the class is a very important meaning as to why using Setters and Getters is actually of benefit. The reason being validation.

Validation

Preventing errors or circumstances when a wrong input will break a whole class.

public function setAccount($account_id)
{
    if (!is_int($account_id) or trim($account_id) == '') {
        throw new Exception("You must provide an Owner");
    }
    $this->accountId = $account_id;
}

The above will check that when setting an account it is only an INT and it cannot be empty otherwise an error ill be thrown.

You can run the same checks for STRINGS or FLOATS.

public function setOwner($owner_id)
{
    if (strlen($owner_id) > 60) {
        throw new Exception("Owner cannot be more than 60 characters");
    }
    $this->accountOwner = $owner_id;
}

The above only allows the owner id to be less than 60 characters otherwise an exception gets thrown. This is the basis for setters and getters in PHP OOP.