The two auxiliary verbs, yào and huì, can be used for talking about the future in the sense of "going to do something" or "intending to do something."
Consider these two sentences:
Wǒ yào qù Běijīng.
我要去北京。
Wǒ huì qù Běijīng.
我會去北京。
我会去北京。
The first sentence, using yào, indicates an intention to go to Beijing. The second sentence, using huì, indicates a confident prediction of going to Beijing.
INTENTION OR PREDICTION
The two sentences above can be translated as:
Wǒ yào qù Běijīng.
I am going to Beijing.
or
I want to go to Beijing.
Wǒ huì qù Běijīng.
I will go to Beijing (I expect I will go to Beijing).
Yào is sometimes (but not always) used with a time expression to differentiate between want and intend. When used without a time reference, the only way to determine the exact meaning of yào is by context or clarification.
Here are some more examples:
Nǐ yào mǎi shénme dōngxī?
你要買甚麼東西?
你要买什么东西?
What are you going to buy?
or
What do you want to buy?
Nǐ huì mǎi shénme dōngxī?
你會買甚麼東西?
你会买什么东西?
What do you expect to buy?
Chén xiǎojie míngtiān yào gēn wǒ shuō.
陳小姐明天要跟我說。
陈小姐明天要跟我说。
Miss Chen is going to speak with me tomorrow.
Chén xiǎojie míngtiān huì gēn wǒ shuō.
陳小姐明天會跟我說。
陈小姐明天会跟我说。
Miss Chen expects to speak with me tomorrow.