"Servicii" was also shown as a translation for "jobs". Isn't that "services"? And, shouldn't "personnel has..." = "personnel have..."?

Please can a native Romanian person explain the difference between "slujbă/slujbe", " muncă/munci" and "serviciu/servicii"...

What is the difference between " slujbe" and serviciu". I see that other have had the same question. Please clarify. Thanks