Как понять английский? Когда произносится "С", а когда "К" ? (англ. буква C)

ca → k
co → k
cu → k
ci → s
ce → s
cy → s
c at the end of a word → k
c before L or R or T → kl or kr or kt (ex. clap, cross, connect)

ch at the beginning of a word and followed by a vowel → usually as in chalk, children (Ч in Russian)
ch in the middle of a word (ex. echo, archaic) → usually k
ch at the end of a word → almost always as in chalk, children (Ч in Russian)
ch followed by an r → kr

tch → very similar to chalk, children. look up examples and listen. If you pronounce it the same as chalk or children you will be approximately correct.

ck → k (c is essentially silent)
C can also be pronounced as sh sometimes, but this is rare. It is most often found in adjectives ending in -cious, such as conscious, precious, ferocious, etc, and also in adjectives ending in -cial, such as special, artificial, crucial, social, etc. One major exception where c is pronounced as sh is the word ocean.

[s] перед i, e, y: cite, center, cyclone
все остальное читается как К

с произносится как ц а к как к