Do Your Best
Hang In There, Good Luck
expression
Remember 頑張る means “to persevere” or “to do one’s best”? This time you're telling someone to 頑張る, so this word means something like do your best, hang in there, or good luck! Speaking of which, 頑張れ, you!
The reading comes from 頑張る. Just watch out for that rendaku on 張る! You've seen it before, but here's a mnemonic in case you need a refresher:
Remember how when it's time to 頑張る (to persevere), you always scream "baa"? Not sure why, but it's a great motivator for you. So you do the same when you cheer for others. When you tell them Do your best, you also scream baa (ば) at them. When you tell them Hang in there, you scream "baa!" If it makes you persevere, it must work the same for others, right? Baa!
頑張れニッポン、負けるなニッポン！
Do your best Japan! Hang in there Japan!
大丈夫だって。春ちゃんならきっと受かるよ。頑張れ。
You'll be fine, Haru-chan. I'm sure you'll pass the test. Good luck!
頑張れ、あとちょっとで助けが来るぞ！
Hang in there, help is almost here!
まあ、結果を気にせずに、頑張れよ！
Well, don’t worry about the results, just try your best!