When an entire tablespace is encrypted, all the data that is stored in this tablespace will be encrypted, so any table created in this tablespace will be encrypted as well.
Here is an example, where the first such tablespace is created, then a table is created and a row is inserted.
›_ Console
SQL> CREATE TABLESPACE securespace
DATAFILE '/u01/app/oracle/product/12.1.0.2/db_1/secure01.dbf'
SIZE 150M
ENCRYPTION
DEFAULT STORAGE(ENCRYPT); Tablespace created.
SQL> alter session set "_ORACLE_SCRIPT"=true;
SQL> CREATE USER user1 IDENTIFIED BY Pwd01 DEFAULT TABLESPACE notsecurespace;
SQL> GRANT DBA To user1;
SQL> CONNECT user1/Pwd01
SQL> CREATE TABLE cust_payment_info
(first_name VARCHAR2(11), last_name VARCHAR2(10), order_number NUMBER(5), credit_card_number VARCHAR2(16) ENCRYPT NO SALT, active_card VARCHAR2(3));