Modal or "flavoring" particles: words used in colloquial speech indicating a certain attitude of the speaker
schon, ja, halt
Although Germans have a fondness for foreign cuisine, they will always stay faithful to their Currywurst (curried sausage). There are an estimated 2,000 sausage stands in Berlin and even a museum solely dedicated to this popular German snack. Berliner Frank Spieß, owner of the unique sausage stand "Curry and Chili," offers 12 levels of spiciness, emphatically ensuring that some, indeed, like it hot!
Also, die Leute haben schon, äh, Spaß daran.
So, the people indeed have, uh, fun with it.
Caption 48, Currywurst - Berlins schärfstes StückPlay Caption
As a modal particle the word schon (in bold) means "indeed" as opposed to the literal meaning "already" when used as an adverb.
Ich bin schon ein Fußballfan, aber kein eingefleischter.
I am indeed a soccer fan but not a die-hard one.
By adding a ja to her sentence, Eva, who takes us on a tour through Berlin's Viktoriapark, implies that it's well-known that the Kreuzberg ("cross hill") isn't really that high with its modest 66 meters.
Das ist ja nicht besonders groß.
That isn't particularly tall.
Caption 14, Berlin - Eva im ViktoriaparkPlay Caption
Halt is another very commonly used modal particle which can be translated as "just", "simply" or "as a matter of fact." Drummer Thomas Holtgreve of German band Frida Gold uses it to add accent, attitude and emphasis.
Ein bisschen auf die Spitze getrieben halt, so.
Just pushed it a little bit to the extreme, so.
Caption 18, Frida Gold - Making of „Zeig mir, wie du tanzt“Play Caption
For a list and more example sentences of German modal particles you can go here and here.
In conclusion, modal particles are uninflected parts of speech used to convey impatience, surprise, disbelief, or urgency along with the statement. Try them out and give your next conversation "auf Deutsch" an authentic, casual feel.
If you want to fine tune your understanding of modal particles go to the Videos tab on german.yabla.com and enter the modal particle you want to practice into the search box. All videos containing said particle will appear. Focus only on watching those clips and your understanding of informal German along with the selected modal particles is sure to improve.