"Thank you, and have a nice weekend."

Translation: Děkuji a hezký víkend.

[Thijs0806]

How do you pronounce ě?

[ChudyBohac]

It's pronounced like the "ye" in "yesterday."
*Note: When "ě" follows the letter "m", it is pronounced as if there was a letter "n" between them. For example, the word "měkký" means "soft" and is pronounced "mněkký."

[VladaFu]

Well, not only that. In this very case "děkuji" is pronounced as [ď e k u j i], so the "d" is palatalized and the "e" is quite the ordinary [e].

[VladaFu]

See the Tips and notes or the Wikipedia article about Czech phonology.

[Bsoluco]

When should I use Dekují and Diký?

[VladaFu]

Děkuji is more formal than Díky. Děkuju is in between and is very universal.

[Bsoluco]

Ok! Děkuju!

[ksturm2]

Why is the "a" pronounced velke a or is that an error with the app?

[VladaFu]

the latter, no need to report

[eugrus]

Should "díky a dobry víkend" be ok?

[VladaFu]

No, no-one says dobrý víkend.

[Deuxy1]

Melo by to byt dekuji a mejte hezky den

[VladaFu]

No, mějte hezký den is not used in Czech and it is an ugly anglicism.