1. Explain it simply
尤其 means 'especially'. It picks out one thing from a group you have already mentioned as the most so.
Before a noun, use 尤其是 - 我喜欢水果，尤其是苹果。
Before a verb or adjective, use 尤其 on its own - 他尤其喜欢打篮球。
尤其 comes in the second part, right before the item you single out, not at the front of the whole sentence.
2. Show examples
他喜欢运动，尤其是打篮球。
Tā xǐhuan yùndòng, yóuqí shì dǎ lánqiú.
He likes sports, especially playing basketball.
尤其是 + the singled-out activity
我喜欢水果，尤其是苹果。
Wǒ xǐhuan shuǐguǒ, yóuqí shì píngguǒ.
I like fruit, especially apples.
尤其是 before a noun
这里冬天很冷，尤其是晚上。
Zhèlǐ dōngtiān hěn lěng, yóuqí shì wǎnshang.
Winter here is very cold, especially at night.
singles out the coldest time
3. Share a tip
Put 尤其是 right before the thing you want to highlight, not at the beginning of the sentence.