s - normal sh sound in english
r - its a alveolar tap, that does't exist in english! (https://en.wikipedia.org/wiki/File:Alveolar_tap.ogg)
a - Its more backwards, (IPA:ɒ) make sure to distinguish it from the hungarian á, which is much more forward! (a = https://en.wikipedia.org/wiki/File:Open_back_rounded_vowel.ogg) (á = https://en.wikipedia.org/wiki/File:Open_front_unrounded_vowel.ogg)
Hope this helped!! :D
a bit less formal shortened form, but still considered formal: viszlát
viszontlátásra /viszlát work for both singular and plural.
If you want something definitely plural (said to multiple people) you can use: sziasztok! szervusztok!
Putting “excuse me, see you later,” gives an incorrect answer. I feel this should be marked correct viszontlátásra, which means see you later. As someone else mentioned as well, you can determine the meaning by looking at its elements. Latni is to see. The -ra also supports this if I understand correctly, it underscores the “to.” Like when you’re roasting someone you say “égésegedRE,” to your health.