According to "Warren Buffett", why Stock valuation is difficult compared to Bond valuation?

Hint: Listen to hls advice #$7$

Bond cash flows and dates are known in advance;

Stock each flows and dates are not known in advance.

Bond cash flows and dates are not known in advance;

Stock cash flows and dates are known in advance.

Stocks are cheaper to buy than Bonds

There are many bonds $(2$ million$)$ to choose from compared to stocks $(1\mathrm{.}000)$