A Developer Edition org has five existing accounts.

The code snippet in question creates and inserts an account namedMyAccountand then initializes a loop to add additional accounts.

The loop runs fromx = 1and continues adding accounts untilx < 10.

Since the conditionx++is post-increment, the loop runs exactly 10 times, creating and adding 10 new accounts to thenewAccountslist.

At the end, theinsertDML statement persists these 10 new accounts, along with the already existing account (MyAccount).

Total accounts in the org:

Existing accounts = 5

New accounts added = 10

Total = 15

Salesforce Apex Developer Guide

Salesforce SOQL & SOSL Reference