My girl seems to understand what we tell her, i.e. put the things in the box, sit down, hand something to someone... but she doesn't say much. She can't even say "o Po" (Grandma) or grandpa.
Oh yes. They understand a lot of thing, but just can't manage tp say it. My girl so far only know "dad dad" and "fa fa"(flowers). Every time she saw a plant, a tree, she says "Fa Fa" loudly
My son can say flower, tree, mum mum (food), auntie, ma ma, baby, tai tai (my cat's name), up (when he wants to go on my bed, the bike, etc.) quite clearly. He says pa pa a lot, but it can mean father, bus, butterfly or bicycle I've been teaching him sign language for several months and he'll do the sign when he tries to say things like butterfly. So even if he's not yet able to speak, I can understand what he's trying to show me. I find it VERY useful.
I think you don't need to worry as their vocal box is not quite developed in this stage and it's clear your baby's hearing is well as he understands what you say.
my girl can say: kitty, pooh pooh, paul paul(婆婆), mama, baba or sometimes daddy, 伯伯, ee, ple ple (apple), 花花, key (mickey), 波波, bye bye, 我, 知, 好,
哎呀, 靚, 腳腳, 手, 早早 (早晨), 姐姐, 比, 不不 (when use the spoon for eating), 食, 味味 (好味), bel s ton (belly botton), 打打, pat pat, mum mum (food)...
仲有d我覺得應該係有意思嘅音 (因為佢成日重覆, 不過我聽唔明)