In a recent year's financial statements, Procter & Gamble Co. showed an unfunded pension liability of $1,032

Question:

In a recent year's financial statements, Procter & Gamble Co. showed an unfunded pension liability of $1,032 million and a periodic pension cost of $151 million.
Explain the meaning of the $1,032 million unfunded pension liability and the $151 million periodic pension cost.