In RSA, can any of the two keys be used for both encryption and decryption?

I know RSA has the concept of "public" and "private" key and one key is used for "encryption" and another for "decryption", but I am confused if both keys can be used for both purposes.. I mean, what you encrypt with any of them, you can decrypt of the other.

There are many incorrect wordings/usages here.
RSA is merely the one publickey cryptosystem that can support both encryption and signature naively in the almost same type of operation.
TextBook RSA
What confuses the people is the Textbook RSA which is simply
c = m^e mod n
for encryption andm= c^d mod n
for decryption, whereassign = hash(m)^d mod n
for signature andverify(m,sign)
that calculateshash(m)
and checks thathash(m) == sign^e mod n
.Both are insecure as you can see that you can multiply the ciphertexts, or .. ( this is a very long story; start from reading Twenty Years of Attacks on the RSA Cryptosystem for more attacks from Dan Boneh).
RSA encryption
RSA encryption requires padding to be secure. PKCS#5v1.5 and Optimal Asymmetric Encryption Padding (OAEP) are the paddings that must be used. The former had lots of attacks due to incorrect implementations. The latter is much easier to implement. They are both proved to be secure so the only problem is the implementations.
RSA signatures
RSA signature requires padding to be secure, too. This time the padding is a Probabilistic Signature Scheme and designed for signatures.
RSA sign!=RSA decryption
Don't use/say that RSA decryption is a signature. It is not. The signatures algorithm consists of two algorithms;
sign
andverify
. During the sign operation, PSS be part of it.For a detailed reading see from Cornell University page; RSA Signing is Not RSA Decryption
Don't use one RSA key for more than one purpose
Don't use the same RSA publicprivate key for more than one purpose. Use either for enc/dec or sign/verify. If you need both, you two different public/private key pairs where the modulus is distinct.
Public key is not for encryption
Public key cryptosystems are slow compared to private key cryptosystems. Therefore we prefer a hybrid cryptosystem where the public key is used for key exchange and the private key is used for encryption. Examples are;
 RSAKEM for Key encapsulation Mechanism and AESGCM for Data Encapsulation Mechanism
 DHKE for key establishment and ChaCha20Poly1305 for data encapsulation mechanism
Where RSA is used today?
In today's security, RSA is mostly used for the signature. Although RSAKEM is promising for key encapsulation there is no standard for that, we use Elliptic Curve DiffieHellman most of the time.