What does that thing on top of “a” stand for?
It’s a long vowel. You spell long vowels a little longer than short vowels. Just click on the play button in the Google Translate.
Slovak is pretty consistent in its orthography, when it comes to accented characters. Whenever you see that little line above a letter, you pronounce the sound longer. Only vowels Á, É, Í, Ó, Ú and liquids Ĺ and Ŕ have a modified length in Slovak. All other sounds are pronounced shortly.
In Slovak there’s a rule of “rhythm”, that short and long syllables should go one after another, like short-long-short-long-short….. It doesn’t always work, but you’ll see plenty of long syllables when reading Slovak text or listening to it.
“Inteligentná” is a borrowing from a non-Slavic language, so I guess it’s one of the reasons why 4 short syllables appear next to each other in the word.
Edit: Oh, “žena” is also 2 short vowels next to each other. As I said, it doesn’t always work.