"鲜" (xiān) is a left-right structured character, consisting of "鱼" (yú) on the left and "羊" (yánɡ) on the right. According to the ancient Chinese people, fish and mutton are the rare and top-grade food. When they are combined into a word, it indicates the extremely fresh and delicious taste.
As an adjective, "鲜" is often used in two contexts in modern Chinese. First, it means "newly picked or not withered; fresh". For example, when a melon farmer peddles his newly-picked watermelons, he may do this way, "新鲜西瓜，新鲜西瓜，快来买!" (Fresh watermelon, fresh watermelon, come and buy!). Here, "新鲜" (xīn xiān) is an adjective made up of "鲜". "新" means "newly picked", and "鲜" refers to the natural sweetness of the newly-picked watermelon.
In addition, "鲜" is used to describe the fragrance of cooked food, usually the soup and the aquatic products. For example, we can sing high praise of the soup made by mom, "妈妈做的鸡汤真鲜!" (mā mɑ zuò de jī tānɡ zhēn xiān), which means "The soup made by mother is divine!". Also, we can exclaim over a cooked dish, "这油焖虾好鲜啊!" (zhè yóu mèn xiāhǎo xiān a), which means "The braised shrimp tastes really good!".
第二，"鲜"也可用来形容烹煮过的食物味美香甜。常用于形容汤汁、水产品等。我们这样称赞妈妈精心烹调的汤：妈妈做的鸡汤真鲜！（mā mɑ zuò de jī tānɡ zhēn xiān）也可以对加工过的成菜由衷地感叹：这油焖虾好鲜啊（zhè yóu mèn xiāhǎo xiān a）！
In the above two contexts, the meanings of "鲜" vary with different types of food it describes. When it is used to describe the natural plants and fruits, it lays emphasis on their freshness as they are newly-picked. When it is used to described cooked food, it stresses the deliciousness due to the superior culinary skills.
When "鲜" is bonded with nouns, many compound words would be generated. In this case, it usually comes before the nouns like "花, 鱼, 肉, 果, 奶, 蘑菇 and 啤酒".
鲜花 (xiān huā, fresh flower)
鲜鱼 (xiān yú, fresh fish)
鲜肉 (xiān ròu, fresh meat)
鲜果 (xiān ɡuǒ, fresh fruit)
鲜奶 (xiān nǎi, fresh milk)
鲜蘑菇 (xiān mó ɡu, fresh mushroom)
鲜啤酒 (xiān pí jiǔ, fresh beer)
The above words are all compound nouns. As their key characters are modified by "鲜", repeated modification should be avoided when they are used in sentences. For example, "这鲜奶真鲜" (literally: the fresh milk is really fresh) is a wrong sentence. The subject "鲜奶" has already described the freshness of the milk, so "真鲜" is unnecessary here. Instead, we can say, "这鲜奶真好喝!" (zhè xiān nǎi zhēn hǎo hē), which means "The fresh milk tastes really good!".
以上词汇经过合成，均为名词。但因其词根已被"鲜"修饰过了。在造句时要避免重复修饰。比如， "这鲜奶真鲜。"这个句子是病句。"鲜奶"作为主语已充分表明了它的新鲜状态。不必再用"真鲜"来强调了。我们可以说：这鲜奶真好喝（zhè xiān nǎi zhēn hǎo hē）。