In the world of finance, "cash" is often shorthand for "cash or cash equivalents".
Instead of the usual layperson interpretation where cash is "a bunch of currency, either physically in my hand or in a bank account", the meaning here is "stuff with incredibly low risk" i.e. you can be very sure that you'll not lose money over time.
Sovereign debt, including bonds, is regarded as the safest type of debt and therefore falls into the 'risk-free' bucket in the finance world. Since cash is usually regarded as risk-free, the word "cash" has come to be a short-hand for "(almost entirely) risk-free assets".
Instead of the usual layperson interpretation where cash is "a bunch of currency, either physically in my hand or in a bank account", the meaning here is "stuff with incredibly low risk" i.e. you can be very sure that you'll not lose money over time.
Sovereign debt, including bonds, is regarded as the safest type of debt and therefore falls into the 'risk-free' bucket in the finance world. Since cash is usually regarded as risk-free, the word "cash" has come to be a short-hand for "(almost entirely) risk-free assets".