Does "serializable" also mean that it's lockable
The definition of serializable schedule is pretty clear. Intuitively, it is a schedule which is equivalent to a serial schedule.

More formally, according to [1] :


  A serializable schedule over a set S of transactions is a schedule whose effect on any consistent database instance is guaranteed to be identical to that of some complete serial schedule over the set of committed transactions in S.


In your example the schedule is definitely serializable, since it is equivalent to running Transaction 2 and then Transaction 1.

I don't know what do you mean by "lockable" and not sure that this term can be applied to a schedule.

[1] R.Ramakrishnan and J.Gehrke, Database Management Systems,  3rd edition